Ukraine President Viktor Yanukovych defiant amid turmoil
Ukrainian President Viktor Yanukovych has insisted that he and his government are doing all they can to solve the crisis in the country.
But the political opposition continued to "inflame" the situation, he added.
The statement was issued in Ukrainian on the presidential website after weeks of often-violent anti-government protests in Kiev and other cities led to a series of government concessions.
It followed an announcement that Mr Yanukovych, 63, was on sick leave.
At the scene
On the streets of Kiev, there's little sympathy for a president with a bad cold.
Protesters seem more concerned with how to force Viktor Yanukovych from power than wishing him a speedy recovery.
They are unimpressed by the concessions which the president claims to have made this week. Ukraine's parliament has repealed controversial anti-protest laws. But, so far, President Yanukovych has yet to sign off on that.
Protesters are underwhelmed, too, by the amnesty for arrested activists passed by the parliament late last night. Opposition leaders have denounced the terms as "unacceptable".
For now, it feels like a stalemate. The protesters remain deeply suspicious of the authorities and determined to stay on the streets.
The presidential website said he had a respiratory illness and a high fever.
The protests began in November after President Yanukovych reversed a decision to sign a trade deal with the European Union, instead favouring a bailout deal with Russia to underpin Ukraine's ailing economy.
Anti-government protesters demanding the president's resignation are still occupying government buildings and manning barricades in freezing temperatures in the centre of the capital.
The past week has seen President Yanukovych accept the resignation of Prime Minister Mykola Azarov and his cabinet, and offer senior jobs to the opposition - offers that were rejected.
The country's parliament has also voted to annul a recently enacted law restricting protests - which appeared to be inflaming the situation - and passed a law giving amnesty to detained protesters, under the condition that occupied buildings were vacated.
"We have fulfilled all the obligations which the authorities took on themselves," President Yanukovych said in the statement.
"However, the opposition continues to inflame the situation calling on people to stand in the cold for the sake of the political ambitions of a few leaders. I think this is wrong."
He added that the opposition was making "ill-considered and irresponsible announcements, thinking about their own ratings more than the life and health of people".
However, striking a more conciliatory note, he added: "From my side, I will show more understanding to the demands and ambitions of people, taking into account the mistakes that authorities always make... I think that we can together return the life of Ukraine and its people to peace."
Some opposition figures expressed scepticism about Mr Yanukovych's reported illness, saying he might be trying to buy time after being forced into concessions in an attempt to calm unrest on the streets.
"This smacks of a diplomatic illness," Rostislav Pavlenko, a member of boxer-turned-politician Vitaly Klitschko's Udar (Punch) party, told Reuters news agency.
Ukraine unrest - key dates
21 Nov 2013: Ukraine announces it will not sign a deal aimed at strengthening ties with the EU
30 Nov: Riot police detain dozens of anti-government protesters in a violent crackdown in Kiev
17 Dec: Russia agrees to buy $15bn of Ukrainian government bonds and slash the price of gas it sells to the country
16 Jan 2014: Parliament passes law restricting the right to protest
22 Jan: Two protesters die from bullet wounds during clashes with police in Kiev; protests spread across many cities
25 Jan: President Yanukovych offers senior jobs to the opposition, including that of prime minister, but these are rejected
28 Jan: Parliament votes to annul protest law and President Yanukovych accepts resignation of PM and cabinet
29 Jan: Parliament passes amnesty law for detained protesters, under the condition occupied buildings are vacated
"It allows Yanukovych not to sign laws, not to meet the opposition, absent himself from decisions to solve the political crisis."
Mykhailo Chechetov, from Yanukovych's Party of Regions, said the president had told supporters in parliament on Wednesday night that he had come to support the passage of the amnesty bill directly from hospital. "He looked ill," Mr Chechetov added.
The EU's foreign policy chief, Catherine Ashton, is in Kiev for talks with both sides. On Wednesday she said she was "shocked" by the violence in the capital and across the country in recent weeks that has left several protesters and police officers dead.
She said Ukraine needed "a political process that is engaged in quickly and properly by everyone", adding: "The responsibility is inevitably going to fall on government to do that as quickly as possible."
Moscow has indicated that it may hold back some of a promised bailout package until a new government is formed.
The loans, totalling $15bn (£9.2bn; 10.9bn euros) and agreed in December, were widely seen as a reward for Kiev's rejection of the EU deal.
Meanwhile a protest leader who had been missing for eight days was found alive on Tuesday evening.
Dmytro Bulatov - leader of the Automaidan motorists' protest - says he was beaten, tortured and left to die by men speaking with a Russian accent.
He is now receiving treatment in a Kiev hospital.