BEIJING, March 16 (Reuters) - China is concerned about an escalation of the war in Ukraine and hopes Moscow and Kyiv will hold peace talks, senior Chinese diplomat Qin Gang told his Ukrainian counterpart on a phone call on Thursday.

China, which has refrained from condemning Russia for its invasion of Ukraine, has urged both sides to agree to a gradual de-escalation leading to a comprehensive ceasefire in its 12-point paper on the "political resolution of the Ukraine crisis".

The plan, which received a lukewarm welcome on both sides, called for the protection of civilians and respect for each other's sovereignty.

"China hopes that all parties will remain calm, rational and restrained, and resume peace talks as soon as possible," Qin told Ukrainian Foreign Minister Dmytro Kuleba, according to a Chinese foreign ministry statement.

Qin added that China hopes Ukraine and Russia will not close the door to a political solution no matter how difficult and challenging the situation, the ministry said.

Kuleba said he and Qin had discussed the "significance of the principle of territorial integrity" during the call.

"I underscored the importance of (Ukrainian President Volodymyr Zelenskiy's) Peace Formula for ending the aggression and restoring just peace in Ukraine," Kuleba wrote on Twitter.

Ukraine has said any plan to end the conflict must involve the withdrawal of Russian troops to Ukraine's borders in 1991, the year the Soviet Union was dissolved.

Chinese President Xi Jinping is expected to visit Russian Vladimir Putin as soon as next week and hold a virtual meeting with Zelenskiy.

Analysts say it will be hard for China to get Russia and Ukraine to the negotiating table, but some pointed out that Xi could act as a "back channel" for starting momentum towards talks.