UNITED NATIONS (AP) — Israel and the Palestinians struck a grim tone over their renewed peace talks at a Security Council debate on Tuesday, with both sides lashing out at each other over recent violence and the Palestinian envoy saying “tangible progress remains elusive.”

UN Under Secretary-General Jeffrey Feltman, however, was more optimistic, saying negotiations have “picked up the pace” since the quartet of Middle East peacemakers — the United Nations, United States, Russia and the European Union — met in September in New York for the first time in more than a year. Feltman said the quartet envoys are now meeting every month to assess the progress.

Under heavy US pressure, the peace talks resumed in July after five years amid deep skepticism and low expectations from both sides. The negotiations are taking place in secrecy and neither side has given details on their content.

At the Security Council, Palestinian Ambassador Riyad Mansour and Israeli Ambassador Ron Prosor gave no signs of budging on long-held stances that have obstructed peace prospects for decades.

Palestinian Ambassador Riyad Mansour accused Israel of taking advantage of the peace talks to step up its settlement building and to attempt “to ease international pressure in this regard.”

“Despite the genuine efforts being exerted, tangible progress remains elusive and hopes are diminishing,” Mansour said.

Prosor dismissed international criticism of settler activity, saying “the real obstacle” to peace is the Palestinians insistence on the right of return for millions of Palestinians refugees and their descendants to what is now Israel. Prosor called that demand “a euphemism for the destruction of the State of Israel and a major hurdle to peace.”

Palestinians reluctantly returned to the negotiating table despite Israeli Prime Minister Benjamin Netanyahu’s refusal to end construction of Jewish settlements in the West Bank and east Jerusalem.

The Palestinians seek the West Bank, east Jerusalem and Gaza Strip, territories captured by Israel in 1967, for their state. Netanyahu has insisted the Palestinians recognize Israel as the homeland for the Jews, but the Palestinians say that demand would undercut the fate of refugees.

Feltman acknowledged that “despite the intensification of negotiations, there have been worrisome developments on the ground that we cannot ignore.” He cited numerous violent acts on the part of both sides, many of them related to settlement activity, which he called “an obstacle to peace and against international law.”

Feltman also condemned the hard-line Hamas movement — which controls Gaza and is not involved in the peace talks — for its construction of a recently discovered tunnel from the territory into Israel. The discovery prompted Israel to suspend the transfer of all construction materials to Gaza, saying militants planned to use the concrete-lined tunnel to attack or kidnap Israelis.

Feltman said “we fully recognize Israel’s legitimize security concerns but we remind Israel officials of the needs of Gaza’s residents, including for construction material for civilian use.”

Prosor delivered a fervent defense of Israel’s decision to restrict the transfer of construction material.

“How many of you have asked us to allow cement into Gaza so the Palestinians can build houses? And yet, when we do in exchange for our goods and goodwill, Israel is repaid with tunnels of terror,” he said.

Copyright 2013 The Associated Press.