(KIEV) - The party of jailed former prime minister Yulia Tymoshenko said on Saturday that the Ukrainian authorities were considering the introduction of a state of emergency in a bid to break up the protest movement against the government.

On Friday, Ukraine's SBU security service announced a criminal investigation into what it said was an opposition attempt to seize power.

"An announcement by the SBU is an element of a use-of-force scenario, planning the possible introduction of a state of emergency," a senior official with the Batkivshchyna party, Grygoriy Nemyria, told AFP.

The opposition has over the past two months been locked in a confrontation with the government of President Viktor Yanukovych.

Ukraine's most severe crisis since gaining independence in 1991 was sparked by Yanukovych's decision to scrap a pact with the European Union in November.

Over the past few weeks the protests have radicalised and turned into an all-out drive to unseat the 63-year-old leader.

The outbreak of violence in which several protesters and policemen were killed is unprecedented in a country which saw the pro-democracy Orange Revolution in 2004 peacefully overturn a rigged election.

Weighing in for the first time since the start of the protests, the military on Friday urged the president to take "urgent steps" to ease the turmoil.

Arseniy Yatsenyuk, leader of the Batkivshchyna (Fatherland) party, told top European dignitaries on Friday that the use of the army against the protesters was "very likely."

"This is one more element of planning the possible introduction of the state of emergency," Nemyria said on Saturday.

"The involvement of the army, this has not happened during the Orange Revolution. This is unacceptable," he added.