The United Nations has added its voice to the condemnation of Israel's plans to expel close relatives of Palestinian militants from the West Bank after destroying their homes.

We believe that these actions will not solve Israel's security problems

Richard Boucher, US State Department

UN Secretary General Kofi Annan said he was "disturbed" by the measures, which amounted to the "collective punishment" of the Palestinian people.

The United States - Israel's staunchest ally - has also criticised the expulsion proposal, as have human rights groups.

The statements followed the arrests early on Friday of 21 Palestinian men related to two militants who, Israel says, organised separate attacks this week which left 12 Israelis dead.

The recent violence led to the postponement of talks between Israeli Foreign Minister Shimon Peres and senior Palestinian negotiators.

But the two sides are now expected to meet on Saturday to discuss ways to ease security and economic conditions for the Palestinians.

Legality

The Israeli army said it had destroyed the homes of the two militants, who are alleged to have organised a double suicide attack in Tel Aviv on Wednesday and an ambush on a bus near the Israeli settlement of Emmanuel on Tuesday.

In one of the attacks, militants bombed a bus and then opened fire

The men, named as Nasser al-Din Assidi of Hamas and Ali Ahmad al-Ajouri of Fatah, are in hiding.

Israeli officials said the authorities were considering exiling the men - all from the West Bank - to Gaza.

But Israel's attorney general has cast doubt over the legality of the plan.

Elyakim Rubinstein said there was no reason the Israeli army should not destroy the homes of those connected with attacks, and those of their relatives, since the High Court had approved similar moves in the past. He is also reported to have backed the arrests of the militants' relatives.

It is the first time the Israeli authorities have taken such a step since the current uprising began.

However, while Mr Rubinstein said that Israel could expel any family members if there was evidence of "their direct involvement in terrorist activities", he did not believe that a sweeping expulsion would be legal.

Condemnation

Israeli Foreign Ministry spokesman Daniel Taub said expulsion could be one way of denying the bombers a "supportive environment".

It is very worrying that the terrorist events are succeeding in confusing the government's thinking

Yossi Sarid, Israeli opposition leader

"If it does prove to be legal and effective, you can rest assured that there is no step that Israel will not take in order to protect its citizens," he said.

But the plan was also condemned by opposition leader Yossi Sarid who said it went against Jewish teachings.

The Palestinian Authority warned that the move would only lead to "more trouble", while the militant Islamic group Hamas threatened to launch a new wave of suicide attacks if any expulsions were carried out.

In a statement, UN Secretary General Kofi Annan said that while he had repeatedly condemned suicide bombings, Israeli self-defence could not justify measures which included the expulsion of relatives to the Gaza Strip or the destruction of their homes.

A US State Department spokesman said such a move would not solve Israel's security problems.

And the BBC's Greg Barrow, at the UN in New York, reports that human rights groups say that the proposed expulsion would amount to a war crime under the Geneva Conventions.