President Pervez Musharraf has sacked two senior officials in Pakistan's North-West Frontier Province (NWFP), which voted to introduce Sharia law on Monday.
The move is a sign of a growing confrontation between the central government and the Islamist leaders in NWFP.
The two sacked men are the head of the provincial police and the chief civil servant.
Their dismissal follows reports of vigilantes attacking targets they consider to be un-Islamic.
Pakistan's federal law enforcers have little jurisdiction over NWFP, which is more strictly conservative than other parts of the country.
"The chief secretary, and inspector general of NWFP police have been asked to report to Islamabad," federal government minister Daniyal Aziz told reporters, according to the AFP news agency.
"New officers will be taking charge in the province."
The BBC's Zaffar Abbas in Islamabad says the decision to replace the two most senior administrative officers of the province is a first clear indication that the federal government and the NWFP are on a collision course.
Senior officials in Islamabad insist that the dismissals have nothing to do with the decision by the provincial government to enforce Sharia.
Our correspondent says this is only partly true.
The decision to replace the two officials was taken following reports that the provincial authorities had failed to maintain law and order in the city of Peshawar
They have been criticised for failing to stop groups of Islamic vigilantes from attacking video shops and billboards in the name of eliminating obscenity.
President Musharraf's government intends to appoint a new chief of police and chief secretary who will ensure law and order prevails.
It is not clear if the provincial government would accept these moves.
Observers say that if it refuses, this could trigger a bigger political crisis in the country.
Wednesday's moves were foreshadowed on Monday when the federal Minister for Information, Sheikh Rashid Ahmed, said Prime Minister Zafarullah Jamali would soon announce "administrative measures" for NWFP.
NWFP's Chief Minister, Akram Khan Durrani, responded by saying any such moves would be unconstitutional.
The bill passed in NWFP gives Sharia precedence over secular provincial law and stipulates that every Muslim will be bound by it.
Details of the law are vague but observers say it sets the tone for the type of rule the province's people can expect.
It proposes restricting the rights of women, and calls for education and financial systems to be brought into line with the teachings of the Koran.
It was passed unanimously on Monday by members of the provincial assembly, which is dominated by hardliners.
Opposition parties withdrew amendments in the face of overwhelming odds.
The bill still needs the signature of the provincial governor to become law. Analysts say that is a formality.
Critics fear a re-run of life under the Taleban, the Islamic hardliners who ruled Afghanistan and drove women and girls out of jobs and schools, back into their homes.
Supporters say all they are trying to do is to curb obscenity and protect human decency.
Human rights groups have condemned the moves towards Sharia, saying the new law could be used to persecute religious minorities.
Hardliners have been cracking down on activities they consider un-Islamic since an alliance of religious parties swept to power in NWFP last October.
Several cinemas have been closed and laws brought in banning the examination of women by male doctors and forbidding men from coaching women athletes.
Civil servants have been ordered to pray five times a day and curbed the sale of music and videos.
The planned creation of a Department of Vice and Virtue has prompted particular concern among some people who recall Taleban vice squads dispensing summary justice in Afghanistan.