BRATISLAVA, April 8 (Reuters) - The head of the Slovak police force said on Wednesday he would demand the dismissal of at least six officers after video footage showed police officers abusing a group of Roma boys in eastern Slovakia.

Interior Minister Robert Kalinak rejected a call by the opposition to resign over the abuse shown on the video, which Police President Jan Packa said was authentic.

"The video clearly shows violation of law... The interior minister has ordered a criminal investigation of abuse of power by a public official," Packa told a news conference.

The Roma form a sizeable minority in many central and east European countries and have long suffered from discrimination in areas such as jobs, education and housing, which has in some places become worse in the current economic crisis.

The video, posted on the web page of the largest daily Sme, showed policemen forcing the Roma boys, aged between 11 and 16, to hit each other in the face, kiss each other and strip naked.

Sme said it had received the video via email. Packa said the incident occurred on March 21, when police detained the six boys in the eastern town of Kosice on suspicion of robbery.

Rights activists say the Roma, also known as gypsies, number around half a million of Slovakia's population of 5.4 million. Most of them live in poverty on the margins of society, receive little education and struggle to find jobs.

Thousands in eastern Slovakia live in slums with no running water or electricity.

Last year, a court sentenced two former policemen to eight and a half years in prison in a case in which a 51-year-old Roma died after being beaten up at a police station in 2001. (Reporting by Peter Laca, editing by Tim Pearce)