Ukrainian forces have come under fire from pro-Russian rebels over 100 times in the last 24 hours, despite a ceasefire coming into force at midnight on Saturday, Ukraine's Foreign Minister Pavlo Klimkin said Monday.

"We and the Ukraine armed forces are fully observing the ceasefire regime but unfortunately in response we have received 112 fire attacks in the past 24 hours from the terrorists of Donetsk and Lugansk," Klimkin said during a visit to Sofia.

The European Union included two Russian deputy defense ministers in its latest Ukraine sanctions list Monday, hitting them with travel bans and asset freezes for their role in the conflict.

The EU's Official Journal named Deputy Defense Minister Anatoly Antonov and first Deputy Minister of Defense Arkady Bakhin for supporting Russian troop deployments in Ukraine.

The controversial sale of two high-tech warships to Russia is "not on the agenda", France's defense minister said on Monday, despite the ceasefire agreed in Ukraine last week.

"It's not on the agenda," Jean-Yves Le Drian told French radio.

The 15 members of the United Nations Security Council will engage in more consultations on the ceasefire in eastern Ukraine, but are not yet ready to adopt a resolution, diplomats said Sunday.

The world peace and security body had been due to vote on a Russian-drafted resolution calling on all parties to implement the deal that provided for a ceasefire beginning on Sunday.

The United Nations Security Council on Sunday urged Yemen's Huthis to cede power, release President Abedrabbo Mansour Hadi and negotiate in "good faith," after the Shiite militia vowed to defy the body's "threats."

Yemen is a traditional U.S. ally in the fight against al-Qaida, but the impoverished Arabian Peninsula country has descended into chaos since the Huthis overran the capital in September.

Residents of the rebel stronghold of Donetsk breathed a sigh of relief on Sunday morning following a first night without bombardments after a fragile ceasefire came into force in east Ukraine.

But despite the sudden outbreak of peace few around the conflict zone seemed confident that the truce would last long after the collapse of previous ceasefire deals.

Fighting dropped sharply across eastern Ukraine on Sunday but there was still sporadic shooting after a ceasefire came into force, the first step in a fragile peace plan aimed at ending 10 months of conflict.

An elderly man and woman died after a Grad missile fire hit the town of Popasna in the Lugansk region some 20 minutes after the truce began at midnight (2200 GMT Saturday), pro-Kiev local governor Gennadiy Moskal said.

Looking east to the bloody conflict gripping Ukraine, NATO-member Poland has kicked off an unprecedented military spending spree worth billions to overhaul its forces as Warsaw believes peace in Europe is no longer a given.

The escalation of tensions with Russia over its annexation of Ukraine's Crimean peninsula and subsequent role in the crisis in that country's east has sounded the alarm on NATO's eastern flank in countries that were under Moscow's thumb during the Cold War.

A ceasefire in Ukraine was cautiously observed by both sides early Sunday, despite accusations by Kiev and the U.S. that Russia had fueled a final push by rebels to gain territory before the deadline.

Ukrainian President Petro Poroshenko ordered troops to abide by the truce from midnight (2200 GMT), in line with a deal reached in Minsk earlier this week with the leaders of Russia, Germany and France.

Both Ukraine and pro-Russian rebels on Saturday pledged to respect a ceasefire due to come into force within hours, after fierce fighting plunged the truce into doubt. 

Under a peace plan signed between Kiev and the rebels in Minsk this week the ceasefire is scheduled to start in war-torn east Ukraine at 2200 GMT on Saturday.