By James Macharia

NAIROBI (Reuters) - Kenyan President Uhuru Kenyatta signed new anti-terrorism measures into law on Friday, triggering fresh protests from opposition MPs who said they would take legal action to overturn the legislation and protect civil liberties.

Kenyatta's move came a day after parliament approved the new laws amid chaotic scenes in which opposition legislators threw books at the Speaker, shouted, chanted and sprinkled water over his deputy.

The president has faced mounting pressure to boost security since Somali al Shabaab rebels killed 67 people in a Nairobi shopping mall in September last year. The Islamist group killed more that 60 people in two attacks this month.

But opposition groups and some activists have said the measures, which will allow suspects to be held without charge for 360 days, up from 90 days, threaten liberties and free speech.

The laws also lay out punishments for media organisations that print material "likely to cause fear or alarm", without defining such material.

It also compels landlords and hotels to provide security officers with information about their tenants and guests.

"I am confident that you will find that there is nothing in this law that goes against the bill of rights or any provision of the constitution," Kenyatta said in a televised address. "Its intent is to protect the lives and property for all the citizens of this Republic."

Kenya's opposition Coalition for Reforms and Democracy (CORD) said it would ask the courts to step in.

"The real target of this 'law' is not terrorism. Its aim is to reintroduce the police state and political hegemony," CORD said in a statement, alluding to the tenure of President Daniel arap Moi from 1978 to 2002 when critics were jailed.

During Thursday's vote in parliament, television footage showed an opposition lawmaker sprinkling water from a bottle on deputy speaker Joyce Laboso, who was reading out the proposed changes to existing security law.

When speaker Justin Muturi took over the reading, opposition legislators jeered and hurled hard-cover books, forcing him to duck. Television footage showed legislators exchanging blows in the public gallery before the vote.

Kenyatta thanked lawmakers for passing the bill "despite the deplorable conduct of a few individuals who seem oblivious to the threat that is upon our country". He said the new law would also tackle radicalisation and cross-border crimes such as poaching and drug-running.