President Donald Trump is being investigated by special counsel Robert Mueller for possible obstruction of justice. US media say senior intelligence officials will be interviewed on whether Mr Trump tried to end an inquiry into his sacked national security adviser, and about the firing of FBI chief James Comey in May. Mr Trump's legal team said the latest leak to the media was ‘outrageous’, and the president has repeatedly denied any collusion with Russia, calling the ongoing inquiry a witch-hunt. The Washington Post sees Mr Mueller’s decision as a major turning point in his investigation, which until recently focused on the Russian angle. Mr Comey, who had previously been leading the Russia inquiries, told Congress last week that Mr Trump had pressured him to drop the investigation into former national security adviser Michael Flynn.