KABUL/WASHINGTON, Aug 20 (Reuters) - Western nations struggled on Friday to ramp up the pace of evacuations from Afghanistan after reports of Taliban reprisals, as U.S. President Joe Biden insisted that the chaos following the American troop withdrawal had not diminished Washington"s international credibility. Facing a torrent of criticism at home and abroad for his handling of the withdrawal and the subsequent swift Taliban takeover, Biden said every American who wanted to would be evacuated, and that about 18,000 people had been airlifted out since July. read more "I have seen no question of our credibility from our allies," Biden told reporters after making a speech from the White House. "... I have not seen that. As a matter of fact, the exact opposite I"ve got ... we"re acting with dispatch, we"re acting, committing to what we said we would do." U.S. evacuation flights from Kabul"s airport had stopped for more than six hours on Friday while U.S. authorities looked for countries willing to accept people fleeing Afghanistan, but they resumed later in the day. NATO Secretary-General Jens Stoltenberg described the situation outside Kabul airport as "very dire and difficult," as several member countries pressed for evacuations to continue beyond Biden"s Aug. 31 deadline. Biden said he could not predict what the final outcome would be in Afghanistan, where the United States and has led a 20-year war with its allies. But he promised to work with other countries to set "harsh conditions" for any cooperation or recognition of the Taliban, based on their human rights record. "They"re looking to gain some legitimacy, they"re going to have to figure out how they"re going to retain that country," he said. "And there"s going to be some harsh conditions, strong conditions we"re going to apply that will depend on ... how well they treat women and girls, how they treat their citizens." Thousands of desperate Afghans clutching papers, children and some belongings thronged Kabul airport where gun-toting Taliban members urged those without travel documents to go home. In and around the airport, at least 12 people have been killed since Sunday, NATO and Taliban officials said. Former government officials told harrowing tales of hiding from the Taliban as armed gunmen went from door to door. One family of 16 described running to the bathroom, lights off and children"s mouths covered, in fear for their lives with the militants at their door. "Those who may be in danger have no clear way out," U.N. High Commissioner for Refugees (UNHCR) spokesperson Shabia Mantoo said, urging neighbouring countries to keep borders open. read more The speed with which the Islamist group conquered Afghanistan, as foreign troops were withdrawing, surprised even their own leaders and left power vacuums. Biden reiterated his contention that the U.S.-funded and -armed Afghan military had been expected to put up more of a fight. "The overwhelming consensus was that ... (the Afghan government forces) were not going to collapse. The Afghan forces, they were not going to leave. They were not going to just abandon and they would put down their arms and take off," Biden said. The Taliban called for unity, asking imams at Friday prayers to persuade people not to leave. Residents in Kabul and four other cities said attendance was low, though prayers passed off without incident. PROTESTS, "DESPITE A TALIBAN GUN" A witness said several people were killed in the eastern city of Asadabad on Thursday when the Taliban fired on a protest. There were similar shows of defiance in two other eastern cities - Jalalabad and Khost - coinciding with celebrations of Afghanistan"s 1919 independence from British control. "The Taliban are facing the new reality of Afghanistan that Afghans are not the same Afghans of 20 years ago," Barakat Rahmati, Afghanistan"s deputy ambassador to Qatar, told Reuters. "Afghans, inclusive of men and women, held protests in Kabul despite a Taliban gun being pointed to them. They are holding protests against injustice. They are defending their identity and their flag." The U.S. State Department announced that nearly a dozen countries, from Europe to the Middle East, would allow flights with people evacuated from Kabul to land. In Britain, media said several senior officials were on holiday as the debacle erupted and that spy chiefs may face a grilling over intelligence failings. Foreign Secretary Dominic Raab countered that the government had been working "tirelessly" on evacuations. Germany said on Friday it was sending helicopters to help, amid reports that one of its citizens had been wounded. Russian President Vladimir Putin said other countries should not impose their own values. Beijing, too, said the world should support, not pressure, Afghanistan. The Taliban ruled with an iron fist from 1996-2001, enforcing a harsh version of Islamic law, before being toppled by U.S.-led forces for sheltering al Qaeda militants behind the Sept. 11 attacks on New York and Washington. This time they are seeking to present a more moderate face. The group said it wants peace, will not take revenge against enemies and will respect women"s rights within Islamic law. There are immediate fears for the Afghan economy, with foreign grants and aid set to slow, funds and assets trapped abroad and GDP predicted to slump. Hundreds of bureaucrats are unpaid for two months, a Taliban official said. read more Reporting by Kabul, Washington and Reuters bureaux worldwide; Writing by Philippa Fletcher, Andrew Cawthorne, Nick Macfie and Patricia Zengerle; Editing by Mark Heinrich, Jon Boyle and Grant McCool Our Standards: The Thomson Reuters Trust Principles.