BRUSSELS, Aug 10 (Reuters) - Six EU member states have warned the bloc"s executive against halting deportations of rejected Afghan asylum seekers arriving in Europe despite major advances of Taliban militants in their country. The Taliban, fighting to reimpose strict Islamic law after their 2001 ouster, have made sweeping gains in their campaign to defeat the government as U.S.-led foreign forces pull out. read more "Stopping returns sends the wrong signal and is likely to motivate even more Afghan citizens to leave their home for the EU," Austria, Denmark, Belgium, the Netherlands, Greece and Germany said in an Aug. 5 letter to the European Commission. "This is why we urge you and your teams at the Commission to intensify talks with the Afghan government on how returns to Afghanistan can and will continue in the coming months," they said in the letter seen by Reuters. Many EU member states are nervous that developments in Afghanistan could trigger a replay of Europe"s 2015/16 migration crisis when the chaotic arrival of more than a million people from the Middle East stretched security and welfare systems and fuelled support for far-right groups. The European Commission said it had received the letter from the six countries and would reply when ready. Asked if the Commission considers Afghanistan a safe country to which asylum seekers can be returned, a spokesman said it is up to member states to make that judgement. The issue is expected to come up at a crisis meeting of EU domestic affairs ministers on Aug. 18, which was arranged mainly to discuss a surge of illegal border crossings from Belarus to EU member state Lithuania, Poland and Latvia. read more "CHALLENGING BUT NOT DESPERATE" Since 2015, around 570,000 Afghans have requested asylum in the EU, the letter from the six EU countries noted, 44,000 in 2020 alone, making Afghanistan the second most important country of origin last year. "We fully recognise the sensitive situation in Afghanistan in light of the foreseen withdrawal of international troops," the countries said, adding that an estimated 4.6 million Afghans were already displaced, many of them in the region. The six countries urged the bloc to look into providing the best support for refugees by increasing cooperation with Afghanistan, Pakistan and Iran. Belgium"s state secretary for asylum and migration, Sammy Mahdi, defended the initiative against criticism. "That regions of a country are not safe does not mean that each national of that country automatically is entitled to protection," he said on Twitter. A senior EU official said some 400,000 Afghans have been internally displaced over recent months and in recent days there has been an increase in numbers of people fleeing to Iran. He described the situation as less dramatic than recent crises in Syria and Iraq because Kabul still has a solid government that the EU can work with. Nevertheless, forced returns of asylum seekers would be difficult now. "Given the context, it is hard to imagine that we would conduct forced return operations for the moment," he said.