Foreign Secretary William Hague is due to speak to his Russian counterpart tomorrow as tensions run high over the future of Ukraine.
Mr Hague has warned that it would not be in Russia's interests to intervene militarily in the crisis on its borders amid fears that Moscow could send in troops.
The Foreign Secretary said there was a "moment of opportunity" in Ukraine after MPs voted to oust president Viktor Yanukovych and hold fresh elections in May, but acknowledged there were "still many dangers" for the country.
Asked about the role of Russia, Mr Hague said Prime Minister David Cameron held talks with president Vladimir Putin last week and he would speak to foreign minister Sergey Lavrov tomorrow.
He said: "It's very important for us to try to persuade Russia that this need not be a zero sum game.
"It's in the interests of the people of the Ukraine to be able to trade more freely with the European Union, it's in the interest of the people of Russia for that to happen as well.
"We are in constant discussion with Russia and it's very important we keep that up, particularly if there's an economic package, it will be important that Russia doesn't do anything to undermine that economic package and is working in co-operation and support of it.
"So, a lot of work to do with Russia over the coming days."
On BBC1's Andrew Marr Show Mr Hague said "we don't know what Russia's next reaction will be" when he was asked if Mr Putin could send in the tanks.
Pressed on whether he believed there could be a Russian intervention he added: "I am not suggesting that. I'm really suggesting that it would not be in the interests of Russia to do any such thing, that we have to keep up the communication with Russia, as we are doing, as you can gather, so that the people of Ukraine can choose their own way forward.
"I'm not suggesting that anybody is going to stop them but there are many dangers and uncertainties."
Mr Yanukovych is believed to be in Ukraine's Russian-leaning east and Mr Hague acknowledged the complex picture in the vast country.
"The political situation even among the opposition is very complex, it's clearly been a very divided country," Mr Hague said.
"There are many dangers but it's urgent that they get on to form that inclusive government, a government of national unity in effect.
"It's urgent that they confirm their constitutional arrangements for elections coming up which they have declared for May.
"It's really urgent that they and we get on with improving their economic situation."
Financial support for the stricken Ukraine economy was something that would be discussed with European partners, the Foreign Office said.
European Union foreign policy chief Baroness Ashton is due to visit Kiev tomorrow to meet key players in the drama, her office said.
Lady Ashton will discuss the EU's support for a lasting solution to the political crisis and measures to stabilise the economic situation.
With Mr Yanukovych refusing to accept the will of the country's MPs, fears mounted that it could split in two - a Europe-leaning west and a Russian-leaning east and south.
He has insisted he is the "legitimately elected president" and had been the victim of "banditry and a coup d'etat".
US president Barack Obama's national security adviser echoed Mr Hague's warning about the dangers of a Russian intervention, saying it would be a "grave mistake".
Susan Rice said. "It's not in the interest of Ukraine or of Russia or of Europe or the United States to see the country split."
Ukraine's parliament voted to temporarily hand the president's powers to speaker Oleksandr Turchinov, a close ally of former prime minister Yulia Tymoshenko.
After spending two-and-a-half years in prison, Ms Tymoshenko addressed the protest movement in Independence Square, but has asked not to be nominated for the post of prime minister in the new administration being formed.
It is thought she may want to focus her energies on campaigning for president, where she could face former heavyweight boxing champion Vitali Klitschko.
"I want to make Ukraine a modern European country," the boxer turned political leader told the BBC. "If I can do that through the president's position, I will do my best."