A controversial act left over from colonial rule was used to detain Ms Kok
Malaysian opposition MP Teresa Kok has been released from jail on Friday, one week after being detained under the Internal Security Act (ISA).
She had been held without charge, accused of campaigning for a mosque to lower the volume of its call to prayer.
A journalist arrested at the same time was released, but two bloggers detained in the past week remain in jail.
Prime Minister Abdullah Badawi is rejecting calls for a vote of no confidence in his government.
His deputy, Najib Razak, was reported by the Associated Press to have suddenly cancelled his planned trip to the Middle East on Friday.
Mr Najib's office insisted the change of plan was not due to concerns about a swelling political crisis at home, but was to allow him time to get to grips with the finance portfolio.
He was given the new portfolio by Mr Abdullah on Wednesday when the prime minister also suggested he might hand power to his successor sooner than his planned resignation in 2010.
Mr Najib was to have visited Saudi Arabia and Bahrain but will now go directly to New York on 24 September to represent Mr Abdullah at the United Nations General Assembly, his office was quoted as saying by AP.
On Thursday, a meeting of top officials of the United Malays National Organisation (UMNO), the leading component of the ruling Barisan Nasional (National Front) government, reportedly urged Mr Abdullah to consider a faster handover of power.
International Trade Minister Muhyiddin Yassin was quoted as saying the meeting expressed "our views and that of the grass roots who want it to be done as soon as possible".
Amid the developing political uncertainties, opposition figures and rights activists, legal and business groups are calling for the ISA to be abolished.
Blogger Raja Petra Kamaruddin remains behind bars
The act, a vestige of British colonial rule, allows for indefinite detention without trial, and was used to jail Ms Kok of the opposition Democratic Action Party (DAP), a journalist and two bloggers in the past week.
Renewed use of the ISA persuaded one minister, Zaid Ibrahim, to resign from Mr Abdullah's government on Monday, and sparked criticism among supporters and opponents of the government.
Political groups both within the ruling government coalition and outside it have spoken this week about the potential for abuse inherent in the ISA.
The United States also released a statement expressing its "grave concern" about Malaysia's use of the ISA to detain opposition political figures.
The US State Department spokesman Sean McCormack said the detention of opposition figures under the ISA would be viewed by the US and the international community as a "fundamental infringement of democratic rights and values".
The blogger detained last Friday, Raja Petra Kamaruddin, and the second detained this week, Syed Azidi Syed Aziz, remain in detention. They have directly criticised Mr Abdullah and Mr Najib in their blogs, calling for political change.
Reuters has reported that the government has issued notices to three newspapers which could see them banned after one reported comments from a junior politician from the ruling party in which he called the country's ethnic Chinese "immigrants" and "squatters".
Mr Abdullah's government remains under pressure from the revitalised opposition led by former deputy prime minister Anwar Ibrahim.
Mr Anwar says he has enough support within the government to topple Mr Abdullah, and has demanded a vote of no confidence in Mr Abdullah's leadership by next Tuesday to prove it.
Mr Abdullah has rejected the calls, describing Mr Anwar's claims of wide support a "mirage".
Mr Abdullah's government lost its two-thirds majority in parliament in elections in March, and has faced growing dissatisfaction over the economy, race and religious relations, and corruption.