French President Francois Hollande has cast doubt on a landmark trade deal between the United States and the European Union, saying it cannot be completed before US President Barack Obama leaves office later this year.

"It's better to let everyone know that France will not be able to approve an accord that still lacks essential elements necessary to guarantee a positive outcome. France prefers to look at things head-on instead of cultivating an illusion that we will be able to reach an agreement before the end of the current US President's term," Hollande said.

Hollande added that the positions of some negotiating parties had "not been respected". His trade chief said France wants to halt talks on the Trans-Atlantic Trade and Investment Partnership agreement, because it is too friendly to US businesses. The EU and the US have been negotiating for three years, and had hoped to reach a deal this year.