UNITED NATIONS, April 24 (Reuters) - U.N. chief Ban Ki-moon said on Tuesday that he was "deeply troubled" by Israel's decision to grant legal status to three settlement outposts in the occupied West Bank, describing the activity as illegal under international law.

The three outposts - Bruchin, Sansana and Rechelim - were built on land Israel declared "state-owned" in the West Bank, an area it captured in the 1967 Middle East war and which Palestinians want as part of a future state.

"The Secretary-General is deeply troubled by the decision of the Government of Israel to formally approve three outposts in the West Bank," Ban's office said in a statement.

"The Secretary-General reiterates that all settlement activity is illegal under international law. It runs contrary to Israel's obligations under the Road Map and repeated Quartet calls for the parties to refrain from provocations," it said.

Israeli officials played down the decision taken by a ministerial committee late on Monday and rejected accusations that the government had effectively created the first new Jewish settlements for more than 20 years.

The United Nations views all Jewish settlements in the West Bank as illegal. However, Israel distinguishes between settlements it has approved and the outposts that were never granted official authorization.

Some 350 settlers live in Bruchin and 240 in Rechelim, both in the northern part of the West Bank, while Sansana, with a population of 240, lies further to the south.

Earlier this month, the so-called Quartet - the European Union, Russia, the United Nations and the United States - criticized Israeli settlement building and called on donors to meet aid pledges to the Palestinians as they sought to revive moribund peace talks.