Russia's foreign ministry says Russia and China have coinciding views on the situation in Ukraine, while the leaders of the G7 group of nations are condemning what they say is Russia's "clear violation" of Ukraine's sovereignty.
Russian forces have bolstered their presence in recent days on Ukraine's Crimean peninsula, where they have surrounded airports and military bases.
Russian Foreign Minister Sergei Lavrov spoke to his Chinese counterpart phone on Monday, and is due to meet with United Nations Secretary-General Ban Ki-moon later in the day in Geneva.
Chinese Foreign Ministry spokesman Qin Gang said China wants to see a political solution to the situation.
"We understand the historical background of the Ukraine issue, and the complexity of the current reality. As I have said yesterday, to get to this point today, things happened for a reason. We hope that all parties can, through dialogue and and consultation, find a political solution, prevent further escalation and work together to safeguard peace and stability in the region."
The G7 leaders issued a joint statement calling on Russia to address any concerns it has with Ukraine through either direct negotiations or mediation led by the U.N. or the Organization for Security and Cooperation in Europe (OSCE). The G7 includes the United States, Britain, Canada, France, Germany, Italy and Japan.
The OSCE is holding a special meeting Monday to discuss how to best support Ukraine.
British Foreign Secretary William Hague is in Ukraine to meet with leaders, and on Monday visited Kyiv's Independence Square.
He said in a BBC radio interview Monday that Russian forces have taken "operational control of the Crimea" and that they must return to their bases there. He blamed Russia for creating a "very tense" and "dangerous" situation, and said European Union foreign ministers will discuss possible diplomatic measures against Russia.
U.S. Secretary of State John Kerry is due to travel to Ukraine on Tuesday, and Mr. Ban has asked his deputy Jan Eliasson to go there as well to ascertain the situation on the ground.
Ukraine's interim government ordered a full military mobilization Sunday in an effort counter what Prime Minister Arseniy Yatsenyuk called a Russian act of war.
Meanwhile, Russian Prime Minister Dmitry Medvedev said ousted president Viktor Yanukovych is still the legitimate leader in Ukraine, and that he was illegally forced from power.
On Sunday, Russian news agencies said President Vladimir Putin told U.S. President Barack Obama late Saturday that Moscow reserves the right to protect ethnic Russians in Crimea and eastern Ukraine.
Also Sunday, Russia's Interfax news agency quoted Crimean parliament speaker Volodymyr Konstanynov as saying parliament will decide Monday on the date of a Crimean referendum that will give voters a choice between independence from Ukraine, continued autonomy within Ukraine or annexation by Russia. The vote was originally set for May 25, but the report said it could be moved up to March 30.
Crimea is a Black Sea peninsula placed under Ukrainian control in 1954 by then-Soviet leader Nikita Khrushchev. It became part of Ukraine when the Soviet Union collapsed in 1991. Crimea has a tiny border with Russia on its far eastern point. The Crimean port of Sevastapol is home to Russia's Black Sea fleet. Most of the people living in Crimea are ethnic Russians, but the region also is home to ethnic Muslim Tatars who generally show disdain for Russia.
Ukraine's troubles began in November when President Yanukovych backed out of a trade deal with the European Union in favor of closer ties and economic aid from Russia. The move triggered weeks of pro-Western demonstrations in Kyiv and elsewhere in Ukraine, and forced the pro-Russian Yanukovych to flee the capital in late February.