Bowing to worldwide pressure and condemnation, Israel on Sunday formally announced an eased blockade of Gaza that could significantly expand the flow of goods overland into the impoverished coastal Palestinian enclave, isolated by the Israelis for three years.

The announcement, made by the prime minister of Israel, Benjamin Netanyahu, came three weeks after a deadly Israeli naval commando raid that thwarted a breach of the blockade by a flotilla of pro-Palestinian aid activists. That raid outraged much of the world and became a catalyst for a serious re-examination by Israel of its policy toward Gaza, which is governed by the militant anti-Israeli group Hamas and is home to 1.5 million Palestinians.

While Mr. Netanyahu did not signal an end to the naval blockade of Gaza or specify precisely what goods would be allowed, his action earned unusual praise from the Obama administration, which has been critical of Israel over the past year and has called the Gaza situation unsustainable.

The White House, which has been pushing Israel for a new approach toward Gaza since the flotilla raid, said that President Obama and Mr. Netanyahu would meet in Washington on July 6, a rescheduling of a meeting canceled after the raid, when Mr. Netanyahu cut short a trip abroad.

There were other new signs of a diplomatic relaxation of the crisis atmosphere that prevailed after the flotilla raid. Mr. Netanyahu announced the Gaza changes jointly in Jerusalem with Tony Blair, the Middle East envoy of the so-called quartet of Middle East peacemakers — the United States, the United Nations, the European Union and Russia. Mr. Blair said the “practical effect” of Israel’s new policy “should change radically the flow of goods and material into Gaza.”

Mr. Netanyahu said that Israel “seeks to keep out of Gaza weapons and war-supporting matériel that Hamas uses” to attack Israel and its civilians. He said, however, “All other goods will be allowed into Gaza.”

In what amounted to a reversal of the system of the last three years, Israel said it would create a list of items not permitted to enter Gaza for security reasons, rather than allowing in only those items that were specifically approved, as before.

In a vague statement of principle last Thursday, Israel said it was ready for “adjustments” in its Gaza policy. But the language of the announcement on Sunday suggested a possibility of more sweeping change. Israel said it would expand operations at the land crossings already operating to enable processing of “a significantly greater volume of goods” and “the expansion of economic activity.” It spoke of opening more land crossings in the future.

It also said it would “streamline the policy” on the entry and exit of Palestinians for humanitarian and medical reasons, and on movement of employees of international aid organizations. “As conditions improve,” it added, Israel would consider “additional ways to facilitate the movement of people to and from Gaza.”

But Israel said that it would maintain the naval blockade, seen as essential to prevent weapons smuggling, and said all cargo bound for Gaza by sea would continue to be delivered via the Israeli port of Ashdod.

On Sunday, the White House said it “welcomes the new policy towards Gaza announced by the government of Israel, which responds to the calls of many in the international community.”

“Once implemented,” the statement continued, “we believe these arrangements should significantly improve conditions for Palestinians in Gaza, while preventing the entry of weapons.”

Still, Israel did not agree to all American demands. Senior American officials, speaking on the condition of anonymity because they were not authorized to speak publicly, said the administration had been pressing Israel to open more land crossings, but that the Israelis were resisting, at least for now.

Both the White House and Mr. Blair signaled that Israel had not gone as far as they wished. “Plainly, there are still issues to be addressed,” said Mr. Blair, the former British prime minister, “and the test of course will not be what is said, but what is done.”

One senior American official echoed him. “We think this is a good move, but obviously implementation is key,” he said. But he added: “Everything that we’d like to see is on there.”

Israel’s relations with Washington have deteriorated over the last year, with America’s anger peaking over the continued building of Jewish homes in East Jerusalem, which the Palestinians want as a capital for a future state. Israel had been hoping to improve its relationship with Washington after the start of indirect, American-brokered talks with the Palestinians in May.

The American-Israeli chill appears to have diminished substantially, the American official said. Even as the administration pushed Israel hard to relax the Gaza border controls, he said the negotiation was more collaborative than combative.

Nine Turks, including one who also had American citizenship, were killed during the raid when violent clashes broke out on a Turkish passenger boat. The episode gravely damaged Israel’s relations with Turkey, its once-close Muslim ally.

Turkey did not immediately seem mollified by Mr. Netanyahu’s announcement. Egemen Bagis, Turkish minister for European Union affairs, said, “If the Israeli government really wishes to prove that they have given up the act of piracy and terror, they should primarily apologize and claim responsibility in the slaying of nine people on May 31.”

Hanin Zuabi, an Israeli Arab member of Parliament who was aboard the Turkish boat, said the announcement amounted to a victory for the flotilla. “This is the beginning of the total collapse of the siege,” she told Ynet, an Israeli news Web site.

Israeli officials said that from Monday, there would be a 30 percent increase in the volume of goods passing into Gaza through the Kerem Shalom crossing.

Israeli sanctions on Gaza began in 2006, after Hamas won Palestinian legislative elections, then led a cross-border raid and captured an Israeli soldier, Gilad Shalit. A strict Israeli embargo has been in place, with Egypt’s help, since Hamas took full control of Gaza in 2007, ousting forces loyal to the pro-Western Palestinian Authority president, Mahmoud Abbas, whose powers are now limited to the West Bank.

Israel said that as part of its easing of restrictions, it will expand the inflow of material for construction projects in Gaza that are carried out with Palestinian Authority approval and under international supervision.

Construction materials had been strictly limited until now, with Israel arguing they could help Hamas build bunkers and rockets. The ban hampered reconstruction after Israel’s three-week military campaign in Gaza that ended in January 2009.