* EU says severity of sanctions will be linked to violence
* Measures include visa and export bans, asset freezes
* EU ministers stay in Kiev (Updates with decision to impose sanctions)
By Adrian Croft and Barbara Lewis
BRUSSELS, Feb 20 (Reuters) - The European Union agreed on Thursday to impose sanctions on those responsible for deadly violence in Ukraine and warned it would ratchet up the pressure if the situation there got worse.
As Ukraine suffered its bloodiest day since Soviet times, EU foreign ministers meeting in emergency session in Brussels agreed measures against Kiev including visa bans, asset freezes and restrictions on the export of anti-riot equipment.
At the same time, the EU pushed forward with its attempt to broker a peaceful solution to a conflict that has left dozens dead, including at least 39 on Thursday.
The foreign ministers of Germany, France and Poland did not come to the Brussels meeting, as planned, after deciding to stay in Kiev to continue contacts with the government and opposition.
"I think (ministers) were truly alarmed, shocked by the scale of violence that has taken place, and that will drive the agenda as it drove the agenda today," EU foreign policy chief Catherine Ashton said.
"The work of the three ministers is crucial on the ground and we will be in constant touch with them to seek their advice and to see what efforts they are able to make, what progress they're able to make," she told a news conference.
The EU decided "as a matter of urgency to introduce targeted sanctions" and asked working groups to begin preparations immediately, a statement said. "The scale of implementation will be taken forward in the light of developments in Ukraine," it added.
The text called for an immediate end to the violence, full respect for human rights and urgent independent investigations into human rights violations.
An earlier draft seen by Reuters on Thursday raised the possibility of an arms embargo, but ministers did not endorse that in the final statement.
Although the EU mentioned no names, officials said those targeted may include ministers, but not President Viktor Yanukovich himself, at least for now. Protest leaders found responsible for violence could also go on the sanctions list.
The initial sanctions list will take days to draw up. The EU could then add more names if the situation deteriorated further, in a policy intended to give the EU leverage to push for a political solution, diplomats said.
British Foreign Secretary William Hague, arriving for the EU meeting, condemned the killing of more protesters in Kiev, calling it "utterly unacceptable and indefensible."
"By permitting such actions to take place, the Ukrainian government is putting itself at odds with reasonable opinion all across the world," he told reporters.
Just three months ago, EU officials had hoped Ukraine would sign a far-reaching trade and cooperation deal with Brussels, provided certain conditions were met. Those included the release of jailed opposition leader Yulia Tymoshenko.
But Yanukovich stunned the EU in late November by spurning the EU deal and instead winning a $15 billion bailout deal from Russia. His move sparked weeks of street protests in Ukraine that escalated this week, causing alarm in world capitals.
Up till now, the EU has sought to promote dialogue between the government and opposition and a peaceful settlement to the crisis.
The bloody assault on protesters in Kiev's Independence Square spurred a dramatic change of heart by EU governments. Until then, they had been largely sceptical about the effectiveness of sanctions on Ukraine, saying they had achieved little in Belarus, Ukraine's northern neighbour.
The United States on Wednesday imposed visa bans on 20 senior Ukrainian government officials believed to be responsible for the violence against protesters. (Additional reporting by Robin Emmott, Martin Santa, Justyna Pawlak, Francesco Guarascio, and Luke Baker; Editing by Larry King)