Al-Qaeda is still "heavily embedded" within the Taliban in Afghanistan, in spite of a historic US-Taliban agreement earlier this year, a senior United Nations official has told the BBC.
Earlier this year, the US signed an agreement with the Taliban committing to withdrawing all American forces from the country by next summer if the Taliban ensured groups including al-Qaeda were not able to use Afghan territory to plot international attacks.
But Edmund Fitton-Brown, co-ordinator of the UN's Islamic State, Al-Qaeda and Taliban Monitoring Team, has told the BBC that the Taliban promised al-Qaeda in the run-up to the US agreement that the two groups would remain allies.
"The Taliban were talking regularly and at a high level with al-Qaeda and reassuring them that they would honour their historic ties," Mr Fitton-Brown said.
He said the relationship between al-Qaeda and the Taliban was "not substantively" changed by the deal struck with the US. "Al-Qaeda are heavily embedded with the Taliban and they do a good deal of military action and training action with the Taliban, and that has not changed," he said.
Eliminating the threat from al-Qaeda and overthrowing the Taliban regime that had harboured them was the original basis for the US invasion of Afghanistan, following the 9/11 attacks. At the time, President George W Bush vowed to hunt the militants until there was "no place to run, or hide, or rest".