KABUL -- More than 2.2 million Afghan refugees have returned home from Pakistan and Iran with UN assistance since March 2002, a spokeswoman for the UN refugee agency UNHCR said on Sunday.

"The number of Afghan refugees who returned to Afghanistan with UNHCR and government assistance since the start of the operation in March 2002 surpassed the 2.2 million mark on Friday," Maki Shinohara told reporters.

While returns have slowed since last year, Shinohara said by Sunday around 400,000 refugees would have returned to Afghanistan this year with UN help, AFP reported.

Nearly 300,000 have returned from Pakistan and more than 100,000 from Iran with UN help while thousands of others have headed home under their own steam.

"If we include the estimate of those who returned on their own, spontaneously, over 500,000 refugees have returned to Afghanistan this year," Shinohara said. The figures were low compared with last year when 1.8 million refugees returned but Shinohara said they were still high compared with other refugee operations, with around 10,000 Afghans continuing to return home every week.

Filipo Grandi, head of UNHCR operations in Afghanistan, said last month most of those refugees who returned last year had strong reasons to come back to Afghanistan -- such as a job, house or land -- or were very poor and seeking better opportunities.

Returns slowed this year as it was harder for the remaining refugees to make a decision to head home.

Grandi also said last year's massive re-entry of refugees had strained Afghanistan's capacity to absorb them.

Around 30 to 40 percent of the population of greater Kabul are former refugees.

Amnesty International in June warned that the "deteriorating" security situation in Afghanistan was not conducive to promoting voluntary repatriation of refugees.

Pakistan and Iran still host millions of Afghan refugees who fled war and famine in their home country over the past two decades.