(Updates with minister treated for injuries)

COLOMBO, Dec 27 (Reuters) - A Sri Lankan minister held hostage by state television employees needed stitches to head injuries on Thursday after they pelted him with stones and sprayed him with paint and urine, officials and witnesses said.

Non-cabinet labour minister Mervyn Silva entered the Colombo premises of state-owned Rupavahini earlier on Thursday complaining that his speech at a ceremony the previous day to reopen a bridge destroyed by the 2004 tsunami was not aired.

His aide then dragged the news director out of the newsroom, tearing open his shirt. The broadcaster's irate staff then hemmed the minister and his entourage into a small room, and would not let them leave, demanding an apology.

Silva was released after he apologised for the incident, but as he was escorted by police to his vehicle, some of the surrounding crowd pelted him with stones and poured dirty water over him. Some members of the crowd told a Reuters reporter at the scene the water was mixed with urine.

"He has some head injuries and we have put stitches. For further observation and treatment we have admitted him to the hospital," said Hector Weerasinghe, director-general of Colombo National Hospital.

Local television showed hundreds of people at the premises shouting and jeering at the minister, who has previously been involved in brawls with the media.

Before he was roughed up, Silva had apologised.

"If my action is considered as a wrong act, I would like to apologise to the employees," he said.

Media Minister Anura Priyadharshana Yapa called the incident "unfortunate". (Reporting by Shihar Aneez; Editing by Simon Gardner and David Fogarty) (shihar.aneez@reuters.com; +94-773-763-577; Reuters messaging; shihar.aneez.reuters.com@reuters.net))