A snapshot of developments in Ukraine, where 26 people have died in two days of fierce clashes between anti-government protesters and riot police, the most bloody episode since demonstrations erupted three months ago:

TUESDAY, FEBRUARY 18

- In the morning, some 20,000 pro-European protesters march from Kiev's iconic Independence Square, where their main camp is based, to parliament to demand a vote on a raft of reforms to strip President Viktor Yanukovych of key powers. The demonstration degenerates into violence, with police using rubber bullets, smoke bombs and tear gas on protesters who throw molotov cocktails and paving stones as they seek to get closer to the heavily-fortified building.

- Protesters briefly seize Yanukovych's party headquarters but later withdraw as smoke billows from part of the building.

- Kiev shuts down the whole of its vast subway network for the first time in the three month-long crisis and limits road traffic into the capital.

- Protesters take back control of Kiev's city hall just two days after vacating the building as part of an amnesty deal.

- In the evening, riot police, hurling stun grenades and using water cannon, break through barricades with armoured vehicles, but face thousands of protesters armed with stones, fireworks and petrol bombs who refuse to obey a 1600 GMT ultimatum to evacuate Independence Square.

- Flames engulf the Trade Union House, which protestors have used as one of their main bases since seizing it almost three months ago. Many tents are also on fire.

- The unrest spreads to the west of the country, where thousands of protesters overrun public buildings in Lviv.

- Late night talks between Yanukovych and the opposition fail to go anywhere, prompting opposition leaders to urge protesters to stand their ground. Yanukovych holds telephone talks with his ally, Russian President Vladimir Putin.

- The European Union, United States and United Nations are among the international voices calling for calm. Top Russian lawmaker Alexei Pushkov says the unrest has been inflamed by the West.

WEDNESDAY, FEBRUARY 19:

- In the morning, security forces appear to have temporarily halted their push to take over the protest camp as people stream to the site with food, clothing and medication for the demonstrators.

- Russia describes the protests as "an attempted coup d'etat".

- The European Union calls an emergency meeting to discuss sanctions against those behind the unrest. France, Germany and Poland lead the calls for sanctions.

- Pope Francis urges an end to violence by both sides.

- Yanukovych calls for a day of mourning on Thursday.

- The UN demands an independent investigation into the clashes.

- Ukraine's security service announces a nationwide "anti-terrorist" operation.