Ben Stiller admits the 'Zoolander' sequel is ''not quite coming together''.

The 'Tropic Thunder' star is hopeful the follow-up to 2001's hit comedy - which was set in the competitive world of male modelling and also starred Owen Wilson - will still happen, but is unsure when further work will be done on the project.

He told Collider.com: ''We have a script, as we've had for a little while, and it's not quite coming together right now but I hope it does. I would like to do it at some point in the future.''

Work on the follow-up began in 2010, with Justin Theroux penning The Script but the film has since ground to a halt.

But Ben has promised the 'Zoolander' sequel will be ''bigger and better'' than the original.

The 46-year-old actor - who plays clueless model Derek Zoolander - previously revealed the sequel will be set in Europe 10 years after the original and will see his character and Owen's alter-ego Hansel no longer relevant on The Fashion scene.

He said: ''I don't want to give away too much, but it's basically Derek and Hansel 10 years later - though the last movie ended on a happy note a lot of things have happened in the meantime. Their lives have changed and they're not really relevant anymore. It's a new world for them.''

Will Ferrell is also expected to return to the series as baddie Jacobim Mugatu.