37 Dead as Ukraine Fighting Intensifies ahead of Peace Summit

Intense fighting in Ukraine, including a devastating rocket strike on Kiev's military headquarters in the east, killed at least 37 people on Tuesday on the eve of a four-way peace summit.

As diplomats scrambled to finalize a deal to end the 10-month war, pro-Russia rebels sought to encircle railway hub Debaltseve and Ukrainian forces launched a counter-offensive around the strategic port of Mariupol.

Ukrainian President Petro Poroshenko said rockets for the first time hit the military's command center in Kramatorsk, the government's administrative capital in the region, well behind the frontlines and far from rebel positions.

The strikes also hit residential areas around the city, killing 15 local residents, officials said. At least 63 people, including five children, were also wounded.

Kiev and the West accuse Moscow of supplying and training the heavily armed separatists, but Russia denies the claims. 

Rebels say their weapons have been captured from Ukrainian forces, although Kiev has cited numerous cases of the insurgents using advanced weapons that are only available from Russian arsenals.

"The shelling is with Vladimir Putin's compliments, who else could have done this?" shouted a Kramatorsk resident as he walked past an unexploded rocket.

- Debaltseve 'encircled' -

Another seven Ukrainian soldiers and eight civilians were killed in fighting over the last 24 hours, Kiev officials and rebels said, including in Debaltseve, which the insurgents claim to have surrounded.

Rebels, who rarely give a military toll, said that seven of their fighters had been killed.

Ukrainian forces took control of three villages east of Mariupol, around 90 kilometers (60 miles) south of the rebel stronghold Donetsk, and fierce fighting raged for control of two more, senior interior ministry adviser Zoryan Shkiryak said.

The violence came as rebels, diplomats and mediators from the from the Organization for Security and Cooperation in Europe (OSCE) went into talks in the Belarussian capital Minsk to bridge gaps on a possible peace deal.

The leaders of Ukraine, Russia, France and Germany hope to sign the deal at a summit in the city on Wednesday, but German Foreign Minister Frank-Walter Steinmeier warned all parties against acts of "sabotage".

"It wouldn't be the first time that an act of political sabotage, a targeted strike, destroys all hopes of a ceasefire," he said.

"That's why I hope that no party to the fighting pushes things to the point where an explosion of violence calls Minsk into question."

French President Francois Hollande and German Chancellor Angela Merkel have been conducting frantic diplomacy, taking the "last chance" deal to Poroshenko and Russian leader Putin. 

Hollande said on Tuesday that he was going to Minsk with the "strong will" to achieve a peace deal.

Merkel was in Washington Monday for lengthy talks with U.S. President Barack Obama on the initiative to defuse fighting that has killed at least 5,300 people since April. 

- No arms, yet -

Obama agreed to hold off on sending arms to Ukraine until truce efforts have played out.

Proponents of sending arms to Ukrainian forces argue that Kiev needs the weapons to counter advanced Russian hardware.

But Merkel has opposed the move amid fears that the Ukraine conflict could become a proxy war between Russia and the West.

Some in the West however say hi-tech weapons could at least make the conflict more costly and painful for Russia, already reeling under the impact of U.S. and EU sanctions as well as low oil prices.

Ahead of the Minsk summit, the European Union decided to hold off implementing new sanctions against Russia.

Putin has warned that a "number of points" still needed to be agreed before the Minsk meeting can take place.

The new plan is based largely on an ignored peace deal agreed in September in Minsk, but a key sticking point is believed to be whether it will extend rebel control over territory seized in recent weeks. 

The new territory amounts to around 500 square kilometers (around 200 square miles), and Kiev is adamant the demarcation line agreed in September should not be shifted. 

Hollande has said the proposal includes the creation of a 50 to 70-kilometer (31 to 44-mile) demilitarized zone around the current frontline.

Other contentious issues include the degree of future autonomy in the east and Kiev's insistence on retaking control of the roughly 400-kilometer border between separatist Ukraine and Russia.