Malaysian Prime Minister Najib Razak says a colonial-era law curbing free speech will be retained and strengthened, backpedaling on a pledge two years ago to abolish the law as part of political reforms.

Rights groups and opposition lawmakers slammed the move, with Human Rights Watch calling it a "major reversal of human rights."

Najib says the Sedition Act will be bolstered to defend Islam and other religions, and to act against those calling for the secession of Sabah and Sarawak states on Borneo island.

He said Thursday that enforcement will be fair to create a more peaceful, stable and harmonious country.

At least 14 people, including opposition lawmakers, academics and a journalist, have been charged under the law since last year, mostly for criticizing the government or ruling officials.