Top US diplomat John Kerry will meet with his Russian counterpart in Rome, amid a toughening American response to a Kremlin-backed separatist insurgency in Ukraine.
Ukraine pressed German Chancellor Angela Merkel and other Western allies on Monday to help settle a pro-Russian uprising that has raged on in the industrial east despite Kiev's unilateral ceasefire.
More than 30 people were killed in a "criminal" blaze in Ukraine's southern city of Odessa, as violence spread across the country during the bloodiest day since Kiev's Western-backed government took power.
US Vice President Joe Biden met Ukraine's new pro-Western leaders Tuesday to offer firm American backing as Washington and Moscow traded blame over an unravelling peace deal to defuse the country's deep crisis.
Russian-US tensions over Ukraine exploded into a public row, as Secretary of State John Kerry refused to attend talks in Moscow after his counterpart snubbed Kiev's interim leaders.
Egyptian army chief and likely new president Abdel Fattah al-Sisi meets top Russian officials on Thursday to negotiate a $2-billion arms deal that is meant to replace subsiding assistance from old ally Washington.
Syria's opposition leader met Russia's top diplomat on Tuesday in a bid to persuade Moscow to pressure Damascus to agree to a transitional government for the war-scarred nation.
Russia warned Tuesday that clashes between opposition and police in Ukraine were getting out of control and slammed the EU's "indecent" support of the protest movement against President Viktor Yanukovych.
After months of tension between the US and Russia, US Secretary of State John Kerry sought to bridge the diplomatic gap by giving his Russian counterpart an unusual gift of potatoes.
Russian Foreign Minister Sergei Lavrov on Saturday said that Western countries appear to have lost "their sense of reality" over the pro-EU protests in Ukraine, which he called the work of provocateurs.
Diplomats insisted they are closing in on an agreement to curb Iran's nuclear programme despite the failure to clinch a long-sought deal in marathon negotiations in Geneva.