The new president of the European Council could be "very important" for David Cameron.
Vin Diesel, star of US action films, has urged the Russian President to take the challenge, but his spokesperson says he's busy.
A three-year-old girl has been found after surviving 10 nights in the Siberian wilderness after her puppy left her side to fetch help.
Russia has called for peace in Ukraine as it tries to push for a ceasefire.
Russia foreign minister Sergei Lavrov urged for a new round of talks on the issue and said: "We call for an exclusively peaceful settlement of this severe crisis, this tragedy."
Pro-Russian separatist leader Andrei Purgin said they were willing to discuss the exchange of prisoners and a temporary ceasefire.
Fighting in eastern Ukraine between separatists and the Ukrainian government has been going on since Russia annexed Ukraine's southern peninsula of Crimea in April.
German Chancellor Angela Merkel has said doing nothing in response to Moscow's actions in Ukraine is "not an option".
She said further sanctions should be imposed even if they impacted on German companies.
"Accepting Russia's behaviour is not an option. And therefore it was necessary to prepare further sanctions," she said.
Seven Ukrainian soldiers have been killed in the past 24 hours, a military spokesman has confirmed.
Earlier the military said Ukrainian paratroopers were fighting a Russian tank battalion in a bid to hold onto the airport outside Luhansk, a separatist stronghold on the border with Russia.
But military spokesman Andriy Lysenko said Ukrainian forces have now pulled back from the airport after being ordered to do so.
Russian President Vladimir Putin has said he "hopes common sense will prevail" in the West over sanctions imposed on his country.
European Union leaders have agreed to ask the European Commission to draw up more measures against Moscow after accusations Russia is sending troops into Ukrainian territory.
Ukrainian President Petro Poroshenko has accused Russia of launching a "direct and open aggression" against Ukraine.
He added there would be "high-level personnel changes" within the Ukrainian armed forces in light of the events of the past few days.
This is in spite of ceasefire negotiation talks due to take place later today.
Russian Foreign Minister Sergei Lavrov has said there will be no military intervention from Russia in Ukraine.
Speaking ahead of talks taking place in Minsk later he called for an "immediate ceasefire without conditions".
He added Russia would defend its economy, citizens and businesses in response to any sanctions imposed on them.
Eight seamen have been rescued after an attack which sunk a Ukrainian patrol boat in the Sea of Azov.
A Ukrainian border guard official said two more men were missing and that a search operation was continuing.
Pro-Russian separatists have claimed responsibility for the attack on social media.
A rescue operation is underway for a Ukrainian naval vessel after it was attacked by artillery from the shore, a government spokesperson said.
Andriy Lysenko said the vessel was a naval cutter. There was no information on the number of people on board.
Pro-Russian rebels claimed responsibility for the attack on social media.
The US, the European Union and Nato should arm Ukraine in its effort to repel a "Russian invasion," according to the chairman of the US senate's foreign relations committee.
Democratic senator Robert Menendez told CNN's State of the Union programme: "This is a direct invasion by Russia. It's not rebels, it's Russian soldiers."
He added that the US, EU and Nato "should be providing the Ukrainians with the types of defensive weapons that will impose a cost upon (Russian President Vladimir) Putin for further aggression."
Asked whether President Obama's administration is considering such a move, he said: "I think that may very well be on the table right now. These are changed circumstances."
Areas of eastern Ukraine where pro-Russian separatists are fighting Kiev government forces should remain part of the country, Russian President Vladimir Putin's spokesman said.
"This is not a conflict between Russia and Ukraine, this is a domestic Ukrainian conflict," Peskov told reporters.
Asked if "Novorossiya" - the name the rebels give to the region in dispute - should remain part of Ukraine, he said: "Of course."