Washington, March 19 (IANS): US President Barack Obama and German Chancellor Angela Merkel have discussed the Ukrainian crisis and the Greek situation in a telephone conversation, Efe news agency reported.

"The two leaders agreed on the need for full and prompt implementation of the three Minsk agreements in order to reach a lasting and peaceful resolution to the conflict," said a White House statement on Wednesday in reference to the crisis in Ukraine.

"They reiterated their agreement that there will be no easing of sanctions imposed on Russia until it has fulfilled all of its Minsk commitments," it added.

US Vice President Joe Biden and Ukrainian President Petro Poroshenko had also addressed the crisis in a phone call on Tuesday.

"As long as Russia continues to fuel violence and instability in Ukraine, the international community must be prepared to increase the costs to Russia for pursuing such actions," said the White House in a statement after their conversation.

On Wednesday, Crimea and the Port of Sevastopol, the Russian Black Sea Fleet's base, celebrated the first anniversary of their accession to Russia accompanied by a massive gathering of support in Moscow's Red Square.

Obama and Merkel "reviewed recent developments in Greece and efforts to reach a pragmatic agreement that builds upon recent reforms to return the country to growth within the euro area", explained the statement.

On Thursday, Greek Prime Minister Alexis Tsipras will meet the leaders of Germany, France, the European Commission, the European Central Bank and Eurogroup President Jeroen Dijsselbloem in Brussels.

The meeting has been organised at the request of the Syriza leader to address the situation in Greece and negotiate with its international creditors at the highest political level.