(KIEV) - Ukraine's Arseniy Yatsenyuk, an opposition leader who has been offered the post of government chief by President Viktor Yanukovych, is a pro-EU former foreign minister who has taken a hands-on role in the protests.

The bespectacled 39-year-old has said he is not accepting or rejecting the proposed compromise and has vowed to press ahead with demonstrations until all the opposition's demands are met.

"We're finishing what we started. The people decide our leaders, not you," he told Yanukovych in a message on Twitter.

The former lawyer does not have the image of a tough politician and his support among the most militant wing of the protesters is uncertain.

But he has taken an increasingly stubborn line in booming speeches on Independence Square in Kiev, the epicentre of the protest movement.

The Ukrainian news weekly Focus said Yatsenyuk has been trying to shed his image of an "intellectual banker" and has been using the daily rallies as a sort of "primary" election for the role of chief opposition leader.

He is also seen by some as a rival as much as ally of fellow opposition leader and former world boxing champion Vitali Klitschko, who currently enjoys greater popularity among potential voters.

In one impassioned address this month, Yatsenyuk gave Yanukovych an ultimatum to solve the crisis and said he was ready to die for the cause.

"If he does not go down that path then we will go forward together and if it means a bullet to the head, then it is a bullet to the head," he said.

For all the fighting talk in front of a crowd, Yatsenyuk is also a skilled behind-the-scenes political operator who has held top posts under previous governments including economy minister and deputy governor of the central bank.

A former speaker of Ukraine's parliament, he was also a fourth-place runner-up in the 2010 presidential election won by Yanukovych -- in which he garnered just seven percent of the vote.

Yatsenyuk led negotiations for the former Soviet republic's membership of the World Trade Organisation and has shown particular attention to the country's fraught economic situation.

Speaking to reporters on Saturday he warned that state coffers were empty and said Ukraine was now "on the brink of bankruptcy".

Political prodigy from opposition stronghold

Yatsenyuk has called for European Union membership for Ukraine and has said he wants to root out deep-seated corruption in the country.

If he accepts the nomination to prime minister, he would be one of Europe's youngest government chiefs, although his authority would be severely limited because of the sweeping powers currently held by the presidency.

That could change, however, as one of the concessions held out by Yanukovych has been a discussion on possible constitutional changes that would boost the prime minister's role.

Originally from Chernivtsi in western Ukraine, a major stronghold for the opposition, Yatsenyuk began his political career in 2001 as economy minister of the pro-Russia Crimean peninsula.

Following the "Orange Revolution" in 2004, Yatsenyuk began pushing a more pro-Western agenda and became a close ally of Yulia Tymoshenko, a former prime minister who is now in prison for abuse of power.

Then president Viktor Yushchenko made him foreign minister in 2007 and Yatsenyuk became a compromise figure when a personal conflict between Yushchenko and Tymoshenko began to spiral out of control.

Unusually for government officials in post-Soviet countries, Yatsenyuk travelled on regular passenger flights while he was minister.

Yatsenyuk and Tymoshenko themselves later had a bitter falling-out, although they have since reconciled and he leads the party of which she was also a founder, which is now Ukraine's second-biggest after the ruling Regions Party.

Yatsenyuk was born on May 22, 1974, into a family of professors at Chernivtsi University and graduated in 1996.

Between 1992 and 1997 he was president of Yurek Ltd, a law firm, and later worked at Aval bank in Kiev.

He is married and has two daughters.