The environmental protestors occupied a 75-metre high chimney for three days at Bernard Road, Sheffield, and daubed the words "toxic crime" down the side in white paint.

Rachel Murray, 29, of London, Huw Williams, 35, of Derby, and Chris Holden, 25, of Kettering, were acquitted of a charge of criminal damage by a jury at Sheffield Crown Court on 2 December.

But they were convicted of a second charge of criminal damage to a door and appeared at Hull Crown Court for sentencing on Friday.

They were protesting about the incinerator after claims it was the worst in the country for breaking pollution laws.

Greenpeace claims the incinerator broke the legal pollution limits 156 times in two years.

The defendants are considering an appeal.