RAMALLAH, West Bank – U.N. Secretary-General Ban Ki-moon said Thursday that he is “deeply troubled” by Israeli settlement building and that it could ultimately prevent the establishment of a Palestinian state.

A day earlier, Israelis and Palestinians had launched formal talks on the terms of a Palestinian state, ending a five-year freeze. The talks were overshadowed by recent Israeli announcements on promoting plans for more than 3,000 new settlement apartments.

The Palestinians want a state in the West Bank, Gaza and east Jerusalem, captured by Israel in 1967. Israel has built dozens of settlements there that are now home to more than half a million Israelis and are deemed illegal by most of the international community.

“I am deeply troubled by Israel’s continuing settlement activity in the West Bank, including east Jerusalem,” Ban said, speaking at a news conference with Palestinian President Mahmoud Abbas.

“The settlement activity is deepening the Palestinian people’s mistrust in the seriousness on the Israeli side toward achieving peace. It will ultimately render a two-state solution impossible.”

The five-year break in Israeli-Palestinian negotiations was largely due to a dispute over settlements.