Ukrainian President Viktor Yushchenko says he is taking direct control of Interior Ministry forces during a time of increasing political tensions.
The president's office says Mr. Yushchenko signed a decree Friday immediately placing Interior Ministry troops under his command.
Interior Ministry spokesman Konstantin Stogniy said the order violates the constitution and insisted the ministry will observe the law. But top commanders of Interior Ministry troops said they will obey the president's orders.
Thursday, Interior Minister Vasily Tsushko deployed troops at the offices of Prosecutor-General Svyatoslav Piskun, shortly after President Yushchenko dismissed the top attorney. The Interior Ministry troops scuffled with the president's security forces at the offices.
Piskun and Tsushko are allies of the president's rival, Prime Minister Viktor Yanukovych.
Meanwhile, the European Union urged President Yushchenko and Mr. Yanukovych to return to the negotiating table and not resort to the use of force.
The EU statement, issued Friday, also calls on the two to resolve the country's political crisis as soon as possible.
In Moscow, Russian Prime Minister Mikhail Fradkov expressed concern about escalating tensions in Ukraine.
President Yushchenko's office, in a statement, said he acted to prevent the use of Interior Ministry troops in the interest of specific political forces.
Mr. Yushchenko canceled a trip to a regional summit in the Czech Republic Friday due to the mounting political crisis.
In dismissing Piskun Thursday Mr. Yushchenko said the top prosecutor violated the country's constitution by combining his position as prosecutor with that of a member of parliament.
In April, Mr. Yushchenko ordered the dissolution of parliament and new elections, but the prime minister's supporters have refused to recognize the action.
Tensions between the reformist president and the prime minister, who favors closer ties with Russia, have been simmering since 2004, when the two men were rivals in a controversial presidential election.
Some information for this report was provided by AFP and Reuters.