UN emergency teams in Pakistan

The United Nations refugee agency says it is sending a large emergency team to Pakistan to prepare for a possible refugee crisis, as thousands of people leave their homes in Afghanistan.

Hundreds of Afghans crossed into Pakistan before it closed its borders, amid fears that the United States will launch attacks on Afghanistan.

Many hundreds more are said to be waiting on the Afghan border.

A BBC correspondent in Islamabad says Pakistani officials are clearly afraid that if the United States does attack Afghanistan, there could be a huge influx of refugees.

The southern Afghan city of Kandahar - the Taleban's headquarters - is almost half-empty as thousands of people continue to leave the major cities including the capital, Kabul, and the eastern city of Jalalabad.

Iran has closed its border with Afghanistan but the UNHCR says, it has been assured by Tehran that it will assist any cross- border operations that may become necessary.

From the newsroom of the BBC World Service