US President Barack Obama says he continues to hope for a diplomatic solution on Crimea but there will be "consequences" for Russia if none is found.
The president spoke at the White House as Secretary of State John Kerry held last ditch talks in London on Friday with Russian counterpart Sergei Lavrov aimed at ending the crisis ahead of a referendum in Crimea on Sunday on leaving Ukraine and joining Russia.
"We continue to hope that there's a diplomatic solution to be found but the United States and Europe stand united not only on (the) message about Ukrainian sovereignty, but also that there will be consequences if in fact that sovereignty continues to be violated," Obama said as he met Irish Prime Minister Enda Kenny.
Washington has signalled that it believes the talks in London and the events surrounding the referendum represent a last chance for Russia to avoid US and European sanctions over its incursion into Crimea.
Obama has described the move into the Ukrainian region as an infringement of international law and there are signs sanctions targeting key Russian political and business figures could be approved as early as Monday.
