We do not want them to leave only to return

UN refugee chief Ruud Lubbers

But its chief, Ruud Lubbers, said UN assistance would mean little if there was no peace for families once they got back to Afghanistan.

"Success will depend on the security in Afghanistan," he said.

"The question is not only to repatriate the refugees but also to ease their reintegration, if possible in their villages, in their families and not in camps.

"We do not want them to leave only to return."

Mr Lubbers will travel to Afghanistan from Iran, where he met President Khatami

Two border crossings have been set up by the UN for use by refugees travelling from Iran, but continuing battles around one means that it has not been opened.

But Mr Lubbers, a former Dutch prime minister, said he was not concerned by the setback.

Several hundred thousand Afghans have returned home from Pakistan under the UN scheme in the last six weeks.

But only about 1,300 people have taken up the UNHCR offer of assistance to return to Afghanistan from Iran, partly because of the closed crossing point.

Mr Lubbers said: "It's limiting our activity a bit, but it's not dramatic and I am not concerned."

Afghan refugees (UNHCR figures, Feb 2002)

In Iran: 1.5m Estimated returns in 2002: 400,000 In Pakistan: 2.2m Estimated returns in 2002: 400,000

He said he believed most areas Afghanistan were safe enough for refugees who had fled war and the Taleban to return.

Mr Lubbers will travel from Mashhad, in eastern Iran, across the border to the Afghan town of Herat.

He will then continue to Kabul and Jalalabad.

Between them, Iran and Pakistan host about 3.5 million Afghan refugees.

Iranian pressure

Mr Lubbers will also be meeting donors and calling on them to produce the cash they have pledged for long-term reconstruction projects to support the returnees.

He has warned that the Iranian Government's patience would not last for ever.

"It's clear that the authorities in Iran simply want people to go home ," he said.

"If we can not deliver the real repatriation, managed with some material assistance, with UNHCR on the ground at arrival points in the villages, then I fear we will see breakdown of trust with the Iranian authorities."