WASHINGTON/KABUL, Aug 11 (Reuters) - Taliban fighters could isolate Afghanistan"s capital in 30 days and possibly take it over in 90, a U.S. defence official cited U.S. intelligence as saying, as the resurgent militants made more advances across the country. The official, speaking to Reuters on condition of anonymity on Wednesday, said the new assessment of how long Kabul could stand was a result of the Taliban"s rapid gains as U.S.-led foreign forces leave. "But this is not a foregone conclusion," the official added, saying that the Afghan security forces could reverse the momentum by putting up more resistance. The Islamists now control 65% of Afghanistan and have taken or threaten to take 11 provincial capitals, a senior EU official said on Tuesday. Faizabad, in the northeastern province of Badakhshan, on Wednesday became the eighth provincial capital to be seized by the Taliban. A doctor based in southern Kandahar said the city was receiving scores of bodies of Afghan forces, and some injured Taliban fighters were also seeking medical support. The fighting was extremely intense in Kandahar city, he said. All gateways to Kabul, which lies in a valley surrounded by mountains, were choked with civilians entering the city and fleeing violence elsewhere, a Western security source there said. It was hard to tell whether Taliban fighters were also getting through, the source said. "The fear is of suicide bombers entering the diplomatic quarters to scare, attack and ensure everyone leaves at the earliest opportunity," he said. Foreign countries are trying to ensure their staff leave Kabul quickly, five foreign security officials told Reuters. One said international airlines were also being asked to evacuate staff. The speed of the Taliban advance has shocked the government and its allies. The group, which controlled most of Afghanistan from 1996 to 2001, when they were ousted for harbouring al Qaeda chief Osama bin Laden after Sept. 11, wants to defeat the U.S-backed government and reimpose strict Islamic law. read more U.S. State Department spokesman Ned Price said the attacks were against the spirit of a 2020 agreement. The Taliban committed to talks on a peace accord that would lead to a "permanent and comprehensive ceasefire," Price said on Wednesday. "All indications at least suggest the Taliban are instead pursuing a battlefield victory." "Attacking provincial capitals and targeting civilians is inconsistent with the spirit of the agreement," he said. The United Nations said more than 1,000 civilians had been killed in the past month, and the International Committee of the Red Cross said that since Aug. 1 some 4,042 wounded people had been treated at 15 health facilities. read more The Taliban denied targeting or killing civilians and called for an independent investigation. read more The group "has not targeted any civilians or their homes in any locality, rather the operations have been undertaken with great precision and caution," spokesperson Suhail Shaheen said in a statement on Wednesday. PEACE TALKS Afghanistan president Ashraf Ghani arrives in Mazar-i-Sharif to check the security situation of the northern provinces, Afghanistan August 11, 2021. Afghan presidential palace/Handout via REUTERS Taliban fighters stand guard at a check point in Farah, Afghanistan August 11, 2021. REUTERS/Stringer A general view of green zone in Kabul, Afghanistan March 13, 2019. REUTERS/Omar Sobhani/File Photo 1/8 Taliban fighters stand guard at a check point in Farah, Afghanistan August 11, 2021. REUTERS/Stringer The loss of Faizabad was the latest setback for the government of President Ashraf Ghani, who flew to Mazar-i-Sharif to rally old warlords to the defence of the biggest city in the north as Taliban forces closed in. Ghani spent years sidelining the warlords as he tried to project the authority of his central government over wayward provinces. Jawad Mujadidi, a provincial council member from Badakhshan, said the Taliban had laid siege to Faizabad before launching its offensive on Tuesday. "With the fall of Faizabad, the whole of the northeast has come under Taliban control," Mujadidi told Reuters. U.S. President Joe Biden said on Tuesday he did not regret his decision to withdraw and urged Afghan leaders to fight for their homeland. Washington had spent more than $1 trillion over 20 years and lost thousands of U.S. troops, and continued to provide significant air support, food, equipment and salaries to Afghan forces, he said. The Afghans "need to determine ... if they have the political will to fight back and if they have the ability to unite as leaders to fight back," White House press secretary Jen Psaki said. She declined to comment on assessments that Kabul could be overtaken by the Taliban in 90 days, which were first reported by the Washington Post, but said the plan to withdraw troops by Aug. 31 held. NEW GENERATION The Taliban advances have raised fears of a return to power of the hardline militants who formed in 1994 from the chaos of civil war. A new generation of Afghans, who have come of age since 2001, fears the progress made in areas such as women"s rights and media freedom will be squandered. The State Department"s Price said the United States was working to forge an international consensus behind the need for a peace accord. The Taliban have captured districts bordering Tajikistan, Uzbekistan, Iran, Pakistan and China, heightening regional security concerns. read more He spoke as envoys from the United States, China, Russia and other countries met in Doha with Taliban and Afghan government negotiators in a bid to break a months-long deadlock in peace talks. But the head of the Afghan reconciliation committee, Abdullah Abdullah, said it was clear the Taliban did not believe in a political solution, Al Jazeera reported on Twitter. Afghan officials have appealed for pressure on Pakistan to stop reinforcements and supplies flowing over the border into Afghanistan. Pakistan denies backing the Taliban. Pakistani Prime Minister Imran Khan said Taliban leaders told him earlier this year that they will not negotiate with the Afghan government as long as Ghani remains president.