Three Malaysian churches were hit with firebombs Friday, extensively damaging one amid a growing conflict over the use of the word Allah by non-Muslims, officials said.

The attacks sharply escalated tensions in the Muslim-majority country ahead of planned protests by Muslims later Friday against a Kuala Lumpur High Court verdict that struck down a three-year-old ban on non-Muslims using Allah in their literature.

"I condemn these actions because they will destroy our country's harmony," Prime Minister Najib Razak told reporters. "The government will take whatever steps it can to prevent such acts."

Najib said he has told the national police chief to step up security at churches and other places of worship.

The Dec. 31 court decision incensed many Muslims, who see it as a threat to their religion. Hateful comments and threats against Christians have been posted widely on the internet, but this is the first time the controversy has turned destructive.

The ruling was on a petition by Malaysia's Roman Catholic Church, whose main publication, the Herald, uses the word Allah in its Malay-language edition.

The first-floor office in the three-storey Metro Tabernacle Church was destroyed in a blaze a little after midnight, said Kevin Ang, a spokesman for the Protestant church. The worship areas on the upper two floors were not damaged and there were no injuries.

Kuala Lumpur police Chief Mohamad Sabtu Osman said a witness saw four people on two motorcycles breaking the glass front of the church and throwing an incendiary object inside before fleeing.

He said police found a wrench, an empty gasoline can and two scorched motorcycle helmets at the scene. The church occupies a corner plot in a row of shops in Desa Melawati, a suburb of Kuala Lumpur.

"We are still investigating," he said. He also urged Muslims not to participate in the planned protests.

Separately, Molotov cocktails were thrown into the compounds of two other churches before dawn, causing minor damage in one and none in the other, church officials said.

Rev. Lawrence Andrew, the editor of the Herald, said many churches have employed extra security guards. "Most churches are taking precautions. They are aware it may just blow up," he said.

The government has appealed the court verdict and the High Court has suspended the decision's implementation until the appeal is heard.