US President Barack Obama promised $1 billion (£597 million) today to boost the military of Nato states in Europe in response to the Ukraine crisis.

The White House also said it would review US troops’ European deployments.

“We need to make sure that the collective defence is robust, is ready and is properly equipped,” the Mr Obama said in Warsaw.

He stopped short of specifying exactly what it would be ready for, but the statement carried threatening echoes of the historic cold-war mentality.

The president did not give a firm commitment to put troops on the ground — something that Poland had wanted — but said more military equipment would be sent to the region.

“I’m announcing a new initiative to bolster the support of our Nato allies here in Europe,” he said.

“Under this effort, and with the support of Congress, the United States will preposition more equipment in Europe.”

Meanwhile, Ukrainian government troops continued a fierce offensive against pro-Russian fighters in the eastern city of Sloviansk for a second day and Interior Minister Arsen Avakov claimed they had advanced past the outskirts.

He added that government troops had broken through rebel positions around the village of Semenovka on the edge of Sloviansk.

Local residents said combat jets and helicopter gunships had attacked rebel positions and heavy artillery barrages had continued throughout the day.

Sloviansk rebel leader Vyacheslav Ponomarev said his had men downed an SU-25 jet and a helicopter gunship, although Kiev immediately denied it.

A military officer said one serviceman had been killed and 13 others wounded when their vehicle came under fire.

The city has seen daily fighting between pro-Kiev forces and pro-Moscow fighters, who have seized government buildings and set up checkpoints around the provinces of Donetsk and Lugansk that constitute Ukraine’s industrial heartland.

Kiev’s acting chief prosecutor Oleh Makhnitskyi said yesterday that 181 people, including 59 servicemen, had been killed in fighting in eastern Ukraine and another 293 had been wounded. 

But with pro-Russian groups controlling several cities in the east, the death toll released by Mr Makhnitskyi is likely to be incomplete.