We are likely to be confronted with space problems if such an influx continues

Fatoumata Kaba UNHCR

"This is the first time in several weeks that we are seeing such a large number of arrivals from Afghanistan," UN official Fatoumata Kaba told reporters in Islamabad.

The exodus is in sharp contrast to the thousands of refugees who had been returning to Afghanistan in recent days.

The new refugees are reported to be stranded in the border area waiting for permission from Pakistan for them to move into proper refugee camps.

More refugees are reported to be getting ready to flee the city of Kandahar.

"We are likely to be confronted with space problems if such an influx continues into the Chaman area," Ms Kaba said.

Single men

Last Saturday it was reported that more than 5,000 Afghan refugees had been returning home every day in the last week, the fastest rate since the fall of the Taleban.

Millions remain in camps

Most of the returnees are single men going home to judge for themselves the country's political and economic outlook before bringing their families.

Katharina Lumpp, UNHCR protection officer for Afghanistan, said it was too early to judge if these people were coming home for good.

"We have to find out how permanent these initial returns will be. From our survey in Iran it is clear people are going to survey sites and see if a return is economically viable," she told BBC News Online.

Too few jobs

Although there is optimism about Afghanistan's newly installed interim government and the chances of peace, the country's economy has been ravaged by years of war and drought. In the cities, jobs are hard to find.

With Afghanistan's harsh winter closing in, relief agencies will not be able to tell for several months if a mass return is likely.

The UNHCR says May and June are traditionally the busiest months for people to return, when snow and winter rainfall have left the ground humid and ready for sowing.

"It will be the winter precipitation, or whether the drought is over, which will determine if people return in the spring," Ms Lumpp said.

As part of a five-year plan, the UNHCR hopes 1 million Afghans will return home in 2002, with half the total coming from Iran and half from Pakistan.