CARACAS (Reuters) - A Venezuelan court has dismissed opposition leader Leopoldo Lopez's appeal against 14-year prison sentence for his role in anti-government protests two years ago, a lawyer representing him said on Friday.

Lopez has become a cause celebre among opposition supporters, who accuse President Nicholas Maduro of trampling of human rights. The U.S. government, the United Nations and international rights groups had also called for Lopez's release.

His sentencing last year upended a brief rapprochement between Caracas and Washington just a few months after the two sides had begun discussions to end more than a decade of acrimony.

Lawyer Juan Carlos Gutierrez gave news that Lopez's appeal had failed in a tweet.

"The sentence was confirmed on the same terms. It's official," Gutierrez wrote.

Lopez was at the forefront of demonstrations demanding Maduro's resignation. Forty-three people died during the protests.

Lopez had publicly called for peaceful resistance to the Maduro government and was behind bars during most of the unrest.

Critics say his trial was a mockery and Lopez, who Maduro refers to as a dangerous criminal, was imprisoned to stifle dissent.

A lead prosecutor later fled the country saying he was pressured to frame Lopez. During the trial, the prosecution had accused Lopez of sending subliminal messages through his speeches that constituted a call to violence.

(Reporting by Brian Ellsworth; Editing by Simon Cameron-Moore)