In the midst of Ukraine's endless political crisis, its embattled president went on sick leave Thursday, setting off a wave of conspiracy theories since protesters have been demanding his ouster for months.

Was 63-year-old Viktor Yanukovych really sick? Or was he feigning illness in preparation for something else, like dodging responsibility for a violent police crackdown on the protesters? Maybe he was ready to give in and hand over power to the opposition but hardliners in his government wouldn't let him?

No one but the president himself knew the answers.

Yanukovych has an acute respiratory illness and a high fever, according to his presidential website. There was no indication of how long he might be on leave or how much work he would be able to do during that time. He was still in charge of the country, his press office said, adding that Yanukovych has taken sick leave twice before.

The president is not known to have serious health problems and the announcement of the leave sparked speculation he was looking for an excuse to avoid further discussions with opposition leaders, which have done nothing to resolve the tensions.

He was also well enough Thursday to upbraid the opposition protesters whose two months of demonstrations demanding his ouster have gripped the country.

Vitali Klitschko, leader of the opposition party Udar, suggested a more ominous reason — that Yanukovych could be pretending to take himself out of action in preparation for imposing a state of emergency. That has been a persistent worry of the opposition since protesters clashed violently with police two weeks ago; three demonstrators were killed in those clashes.

"I remember from the Soviet Union it's a bad sign — a bad sign because always if some Soviet Union leaders have to make an unpopular decision, they go to the hospital," Klitschko said.

Some suggested the sick leave could be a ruse to take him out of power, as in the attempted coup against Soviet leader Mikhail Gorbachev in 1991.

"I don't remember official statements on Viktor Yanukovych's colds. But I remember well, when on Aug. 19, 1991, the vice president of the USSR, Gennady Yanayev, announced the serious illness of Mikhail Sergeyevich Gorbachev," political commentator Vitaly Portnikov wrote on his Facebook page.

Although the coup failed, it accelerated the collapse of the Soviet Union, which officially was dissolved four months later.

Still others took the presidential announcement at face value. Analyst Mykhailo Pohrebinsky noted that Yanukovych had made a late-night visit to parliament Wednesday amid tense discussions and "those who were close to him said he really was very pale and exhausted."

In any case, Yanukovych later Thursday issued a statement saying "the opposition continues to escalate the situation and urges people to stand in the frost for the sake of the political ambitions of several of its leaders.

Cold nights in Kyiv for protesters

Temperatures in Kyiv have dropped as low as –20 C (–4 F) on some nights, bringing severe discomfort to those manning a sprawling round-the-clock protest tent camp on Kyiv's main square.

Yanukovych has faced two months of large protests that have sometimes paralyzed the centre of Kyiv, the capital. The protests started after he backed out of a long-awaited agreement to deepen ties with the European Union, but quickly came to encompass a wide array of discontent over corruption, heavy-handed police and dubious courts.

Despite offering several concessions, authorities have so far failed to mollify the protesters.

In a series of moves aiming at resolving the crisis, parliament voted Tuesday to repeal harsh anti-protest laws. Yanukovych must formally sign that repeal and it was unclear whether he could do so while on sick leave.

He also has accepted the resignation of his prime minister. But protesters say the moves are insufficient — they want him out and new elections held.

On Wednesday, the parliament passed a measure offering amnesty to some of those arrested in the protests. That new law, however, was only valid if demonstrators vacate most of the government buildings they occupy in Kiev and in some western cities. The offer was quickly greeted with contempt by the opposition, which regards the arrests during the protests as fundamentally illegitimate.

Conflicting numbers

There are conflicting figures on how many protesters are now in custody. One opposition lawmaker said Wednesday there were 328, whom he characterized as "hostages." But the prosecutor-general's office said Thursday there were 140.

Interior Ministry head Vitali Zakharchenko said a 30-year-old policeman at the protest front lines in Kiev had died of a heart attack overnight. Although there have been no clashes there for several days, tensions at the site are heavy. Zakharchenko said the policeman's death was "a consequence of the daily stress."

After stepping back from the agreement with the EU, Yanukovych got a $15 billion aid package from Russia that also gives Ukraine lower prices for the Russian gas upon which the country depends. That aid from Russian President Vladimir Putin is key to propping up Yanukovych and keeping the struggling Ukrainian economy from bankruptcy.

But as the crisis drags on, concerns are rising about whether Russia will keep its financial commitment if the Yanukovych regime collapses.

Putin said Wednesday the aid would still be valid, but suggested that delivery of the next tranche could be delayed until the formation of a new Ukrainian government. That appeared to refer to waiting until a new prime minister is named.