Yulia Tymoshenko to run for Ukraine leader
Former Prime Minister Yulia Tymoshenko has said she plans to run for president of Ukraine in May elections.
She was released after serving three years in jail in February following the ousting of President Viktor Yanukovych.
It was followed by a referendum which led to Russia's annexation of Crimea. On Thursday, the UN General Assembly voted to declare it invalid.
Earlier, the International Monetary Fund (IMF) agreed to a loan deal with Ukraine worth $14bn to $18bn.
US President Barack Obama said the IMF announcement was a "major step forward" to help Ukraine stabilise its economy and meet the long-term needs of its people.
Speaking after talks with Italian Prime Minister Matteo Renzi in Rome, Mr Obama said it was a "concrete signal" that the world stood united with Ukraine at a difficult time.
The US Senate and House of Representatives have both passed legislation backing a $1bn loan guarantee to Ukraine, which still has to be signed into law by President Obama.
Ukraine's interim Prime Minister Arseniy Yatsenyuk had earlier told parliament the country was on the ""on the edge of economic and financial bankruptcy".
At the UN General Assembly, 100 countries voted in favour of a resolution declaring the Crimean referendum on 16 March illegal and affirming Ukraine's territorial integrity.
Eleven nations voted against, with 58 abstentions. Given that the resolution was non-binding, the vote was largely symbolic, says the BBC's Nick Bryant in New York.
But Ukraine hopes the resolution will act as a deterrent and dissuade Moscow from making further incursions into its territory, he adds.
Yulia Tymoshenko announced on Thursday her candidature for Ukraine's presidential elections in May.
Ms Tymoshenko, who has already served twice as prime minister and ran for president in 2010, told reporters she would stand as "a candidate for Ukrainian unity".
She said she had earned the right to be considered a candidate who was against corruption.
"My presidential campaign will be the campaign of direct action: no promises, but immediate actions, and then - in a couple of days - reporting on what's been done," she said.
Ms Tymoshenko was a major figure in the 2004 "Orange Revolution" that ousted Mr Yanukovych from the presidency after an election widely seen as fraudulent.
She was imprisoned in 2011 for corruption linked to a gas deal she brokered with Russia as prime minister in 2009.
Her supporters say the case was politically motivated and instigated by Mr Yanukovych, to whom she lost the 2010 presidential election.
On Monday she denied the authenticity of a taped conversation in which she allegedly called for Russia to be turned into "scorched earth" and for ethnic Russians in Ukraine to be killed.
Ms Tymoshenko said the recording, which featured prominently on Russian news reports, was produced by Russia's security services.
Former boxer Vitaliy Klitschko and chocolate tycoon Petro Poroshenko are also expected to take part in the presidential election.
Opinion polls suggest Mr Poroshenko, who is one of Ukraine's richest men, is currently the most popular candidate.
The election is expected to take place on 25 May.
'Door of diplomacy'
More than 100 people were killed during protests which overthrew pro-Kremlin President Yanukovych in February.
They followed months of street protests sparked by Mr Yanukovych's decision to reject a planned EU trade deal in favour of closer ties with Moscow.
Since then, Russia has annexed the Crimean peninsula, which last week voted to become part of the Russian federation.
The West has widely condemned the move, with US President Barack Obama warning on Wednesday of further EU and US sanctions against Moscow if there were any further incursions.
Mr Obama said on Thursday that the US hoped Russia would "walk through the door of diplomacy" and resolve the issue in a peaceful way.
In other Ukraine developments:
- Six Ukrainian military officers detained by Russian troops in Crimea have been released, but five remain in custody; those released include Col Yuli Mamchur, the commander of Belbek base which fell on Saturday
- Ukrainian Prime Minister Arseny Yatseniuk says the price Ukraine pays for Russian gas will increase by 79% from 1 April
- Russian President Vladimir Putin announces plans for a new domestic payment system to circumvent financial sanctions imposed by Western nations over the Crimea issue.