UPDATE 3-EU urges Russia to back Ukraine peace plan
* EU holds out threat of more sanctions
* EU member states divided over tougher sanctions
* EU to send team to advise Ukraine on police reform (Updates with ministers' comments, statement)
LUXEMBOURG, June 23 (Reuters) - The European Union urged Russia on Monday to back President Petro Poroshenko's peace plan for Ukraine but its threat of tougher sanctions if Moscow failed to do so appeared to only have partial support.
EU foreign ministers meeting in Luxembourg held out the 15-point plan put forward by the new Ukrainian president as an opportunity to defuse the crisis that has led to hundreds of deaths and caused a confrontation between Russia and the West.
They called on Russia to "support the peace plan and to adopt effective measures to stop the continued flow of illegal fighters, arms and equipment over the border into Ukraine".
The ministers' statement noted the EU has been drawing up further sanctions that could be imposed on Russia if events in eastern Ukraine required it.
But ministers' comments again showed divisions among the EU's 28 member states about pushing ahead with tough economic sanctions against Russia they have been threatening since March.
British Foreign Secretary William Hague said EU leaders would weigh Russia's actions at a summit on Friday and warned Russia that the EU was ready to impose tougher sanctions if it was not satisfied with Moscow's response to Kiev's peace plan.
"(Russian President Vladimir) Putin should be in no doubt that in the EU we are ready to take those measures," he said.
But Dutch Foreign Minister Frans Timmermans said that whether EU leaders adopted more sanctions against Russia on Friday depended on developments between now and then.
"I think the need is to stimulate all parties to negotiate and try and avoid the need to escalate the sanctions. I hope that we can avoid that step," he said.
German Foreign Minister Frank-Walter Steinmeier, who will travel to Kiev to meet Poroshenko on Tuesday, said he told other EU ministers it was clear that if nothing moved in the right direction, the question of sanctions "immediately will be in front of our door again".
"But I've pleaded that we should concentrate on getting some elements of Poroshenko's peace plan to work at a time when Poroshenko showed courage with this plan," he said.
The United States has already threatened sanctions on Russia's financial, defence and high-tech industries as more Russian military equipment has flowed into Ukraine, and has intensified talks with Europe over imposing similar measures.
But many of the EU's member states are wary of antagonising their major energy supplier and concerned about Russian retaliation if they imposed tough trade sanctions on Russia.
So far, the EU has imposed limited measures, targeting 61 people in Russia and Ukraine with asset freezes and travel bans, as well as two energy companies in the Ukrainian peninsula of Crimea, taken over by Moscow earlier this year.
Britain, France, Poland, Sweden, Denmark, the Czech Republic and the former Soviet republics in the Baltics have pushed for tougher sanctions on Russia while Italy, Greece, Cyprus, Bulgaria, Luxembourg, Austria, Spain, Portugal and Malta have been among the most reluctant EU states.
Ukrainian forces began a seven-day ceasefire on Friday, as part of the president's plan to end a rebel insurgency in the east of the country. But on Saturday, pro-Russian separatists attacked Ukrainian posts on the border with Russia and a military base, government forces said.
Putin said on Saturday he supported Ukraine's ceasefire, but added that without "practical action" to start negotiations the plan would not be viable.
The EU ministers held talks with new Ukrainian Foreign Minister Pavlo Klimkin who told reporters that the critical thing was that the ceasefire became solid.
"Also critical is support from the Russian Federation and the influence of the Russian Federation on these groups (of rebel fighters)," he said.
Putin discussed the peace proposals with U.S. President Barack Obama on Monday.
Ukraine is due on Friday to sign a free-trade deal with the EU. Former Ukrainian President Viktor Yanukovich refused to sign that agreement last November, prompting an uprising that brought him down and led to Russia annexing Crimea in March.
As part of their wider response to Russian actions, EU foreign ministers approved on Monday new rules prohibiting the imports of goods originating in Crimea into the EU.
They also agreed to send experts to advise Ukraine on reforms to its police and justice system. The team is expected to be sent to Ukraine in the coming months.
Separately, a NATO official said alliance foreign ministers meeting in Brussels later this week would discuss a proposal to set up a "trust fund" to help strengthen Ukraine's armed forces in the areas of logistics, command and control, communications and cyber defence. (Additional reporting by Tom Koerkemeier and Sabine Siebold in Luxembourg, Julia Fioretti in Brussels and Pavel Polityuk in Kiev; Editing by Alison Williams)