ROME (Reuters) - Russian troops entering Ukraine is "an intolerable escalation" of the crisis there, Italian prime minister Matteo Renzi told Russian President Vladimir Putin by telephone on Thursday.

Ukraine accused Russia of bringing troops into the southeast of the country in support of pro-Moscow separatist rebels. Russia says reports of the presence of Russian military units in Ukraine bear "no relation to reality".

"Referring to the very serious news of Russian troops entering Ukraine today, Prime Minister Renzi reiterated that this is an intolerable escalation and would have very grave consequences," Renzi's office said in a statement.

Renzi, who as Italian Prime Minister currently holds the six month rotating presidency of the European Union, called on Putin to "rapidly return to the negotiating table".



(Reporting by Isla Binnie)