Damascus-based Hamas leader Khalid Mashaal said Tuesday that the direct talks between the Palestinian National Authority (PNA) and Israel are illegal and under U.S. coercion.

"The direct negotiations lack for the Palestinian and Arab approval, which means they lack for the legitimacy," Mashaal said during an Iftar (the meal after fast over) on Tuesday.

"Palestinian negotiators are isolated as they bet on the United States instead of the Palestinian people," he said.

"I call on adopting an alternative Palestinian strategy that based on resistance principle, rebuilding the Palestinian Liberation Organization (PLO)'s foundations and unifying the Palestinian people," said Mashaal.

Mashaal also called on Egyptian and Jordanian leadership not to join the negotiations.

Israel and PNA have earlier accepted an U.S. invitation to attend a meeting in Washington on Sept. 2 to relaunch direct talks following a 20-month hiatus.

However, Damascus-based Palestinian political factions rejected the PNA's decision to hold face-to-face talks with Israeli Prime Minister Benjamin Netanyahu's government.

Meanwhile, Netanyahu said on Sunday that he wanted to "surprise the skeptics" by reaching a settlement with the PNA at the U.S.- sponsored direct talks.