Najib Razak is expected to take over as prime minister by early April
Malaysia's government has imposed a ban on two main opposition newspapers, ahead of key political developments.
Harakah and Suara Keadilan have been told they cannot publish for the next three months, with immediate effect.
It comes a week before the expected designation of a new and controversial prime minister, Najib Razak, and two weeks before important by-elections.
Analysts say the government, which has faced strong opposition challenges, is increasingly intolerant of criticism.
The government announced its decision in a letter from the Home Ministry addressed to the head of the Suara Keadilan newspaper.
"This latest suppression underscores the insecurity and fear that Najib and his supporters feel about their political situation," Tian Chua, a spokesman for the newspaper, is quoted by AFP news agency as saying.
"We fear that this action by the government is a prelude to a general clampdown on press freedom in Malaysia," he said.
Mr Chua said that no reason for the ban had been given, adding that the newspapers would defy it despite the threat of legal action.
Harakah and Suara Keadilan are the main publications of the Pan-Malaysian Islamic Party and the People's Justice Party, which belong to a three-party opposition alliance that has made major inroads against the ruling National Front coalition in the past year.
Mr Najib is expected to take office by early April when the current prime minister, Abdullah Badawi, steps down.
The transition will follow a turbulent period in Malaysia, which has seen growing political conflict and protests from angry minority groups.
Mr Najib would also enter office amid a series of allegations, including one linking him to a murder case, all of which he strongly denies.