Matt Damon's upcoming Bourne sequel has been thrown into jeopardy - the action franchise's director has reportedly quit the project.

Paul Greengrass joined the film series by taking charge of 2004's The Bourne Supremacy and he returned to direct a second sequel, The Bourne Ultimatum in 2007.

Damon recently announced he is working on a fourth movie, teaming up with Greengrass to develop an original story for the next installment in the popular series, which is based on the books by Robert Ludlum.

But the film has been thrown into doubt amid reports Greengrass has walked away from the project, according to Theplaylist website.

The site reports Greengrass quit after bosses at Hollywood studio Universal hired their own writer to look after the script, without consulting the director.