A former leading federal prosecutor has claimed he was sacked by Donald Trump after he refused to take the president's repeated and "inappropriate" phone calls.

Preet Bharara, who served as a United States district attorney in New York, said Mr Trump tried to contact him on three occasions, whereas his predecessors, President Obama, did not call him a single time in seven and a half years.

Mr Bharara said he refused to take the calls as he was uncomfortable about fostering close contact between the White House and independent criminal investigators.