Amnesty International has warned that a Malaysian security law that comes into force Monday will give the government "unchecked and abusive powers" in a blow to human rights.

The National Security Council Act gives sweeping powers to a council led by embattled Prime Minister Najib Razak, who faces pressure to resign over a financial scandal. The council can declare a state of emergency in areas deemed to be under a security threat, impose curfews and have wide powers of arrest, search and seizure without a warrant.

The law is aimed at countering terrorism threats but critics fear Najib will use it as a tool to hold on to power.

The rights group said Monday the government has "spurned checks and assumed potentially abusive powers" with the new law.