Ukraine's presidential election must be allowed to go ahead as planned on May 25, Foreign Secretary William Hague said as he attended a Council of Europe summit ahead of a visit to the strife-wracked country.
Mr Hague has warned that Moscow appears to be provoking violence in the largely Russian-speaking east of Ukraine in a bid to destabilise the country and prevent the vote taking place.
Leaders of the anti-government movement have said they will pre-empt the presidential poll by holding a referendum on autonomy for eastern regions on May 11.
An international agreement to defuse the situation sealed in Geneva last month has failed to halt the violence in the east of Ukraine, where 30 pro-Russian insurgents were killed in a government operation to regain control over the city of Slovyansk.
Arriving at the Council of Europe meeting in Vienna, Mr Hague said the doors remain open for a diplomatic solution to the crisis, but added that Russia must show it is ready to implement any agreement to which it signs up.
The agreement reached between Russia, Ukraine, the US and the EU in Geneva called on illegal armed groups to lay down their weapons and vacate buildings in exchange for a broad amnesty, but both Kiev and Moscow have since accused each other of not pressuring their supporters to disarm and Vladimir Putin's spokesman has suggested that the viability of the deal was being destroyed by military operations against anti-government protesters.
At the start of today's talks on Ukraine in Vienna, Mr Hague said: " There will be a very strong message from the great majority of countries today that the Ukrainian elections must be allowed to go ahead.
"But of course we also remain open to every diplomatic opportunity. The diplomatic doors remain open.
"If there is a way of putting new life into what was done at Geneva three weeks ago, then we should try that, but it would have to be on the basis of countries that are there, the organisations that are there, really implementing what they have committed themselves to do. Last time, Russia came to Geneva and then did not take a single action to implement the agreement that had been made."
Following today's meeting, Mr Hague will fly to Kiev for talks tomorrow with the interim government established following the overthrow of pro-Russian president Viktor Yanukovych in February.
He will also visit Moldova and Georgia, which have also been at the centre of the struggle for influence between Moscow and the West in the former Soviet sphere.
Speaking yesterday before he began his five-day trip, Mr Hague said: "Moldova, Ukraine and Georgia have all made great efforts to build free societies and they deserve our backing. In each case, they need to carry out substantial reforms to ensure the rule of law and sustainable economic development, especially in tackling corruption.
"Clearly Ukraine is under immense pressure from Russian attempts to destabilise the country, provoke violence and, it seems, prevent elections happening later this month.
"The Ukrainian people want what people everywhere want: to live in a free country where the law applies fairly to everyone, a Ukraine where people have a chance to build decent lives for themselves rather than have their economy looted by corruption.
"We stand with them in their efforts to create a better Ukraine.
"I will urge the Ukrainian government to carry forward much-needed reform, and assure them of practical help from Britain.
"I will discuss Ukraine's plan for elections on May 25, and meet three leading presidential candidates to hear their views on how best to ensure Ukraine's long-term future as a successful, independent, united, and sovereign nation."