KENYAN opposition lawmakers have disrupted a vote to authorise tough terrorism-related measures that rights activists say threaten civil liberties and free speech, forcing the parliamentary speaker to postpone the session.

Television footage showed members of the opposition yelling, tearing up papers and shouting down the speaker of parliament, Justin Muturi, who then suspended the session and said it would resume in the afternoon.

President Uhuru Kenyatta has faced mounting pressure to boost security since an attack in September 2013 on Nairobi's Westgate mall that left 67 people dead.

He has urged lawmakers to pass the amendments, which include extending the time suspects can be held without charge to 360 days from 90 days.