Cameron told a British parliamentary committee that Britain would help develop an infantry training program to improve the "durability" of Ukrainian forces and deter challenges by Moscow.

They would include specialists in tactical intelligence to medical care, he said.

"If we don't stand up to Russia in the long-term it will be deeply damaging to all of us because you'll see further destabilization. Next it'll be Moldova or one of the Baltic states," he said.

Cameron (pictured center) ruled out a direct military solution to Ukraine's crisis that erupted early last year when Russia annexed Crimea and separatists seized eastern Ukraine.

On Tuesday, a fresh ceasefire bid remained fragile, with Kyiv accusing separatists of trying to seize the Ukrainian port city of Mariupol.

"There needs to be a diplomatic solution which I think should be enabled by sanctions and pressure and the economic weight of Europe and America," Cameron said, referring to current Western bans on business with Russia.

Britain's defense minister said up to 75 personnel would be deployed for six months.

Four-way talks in Paris

Cameron spoke shortly after four-way talks in Paris involving the foreign ministers of Ukraine, Russia, France and Germany.

Ukrainian Foreign Minister Pavlo Klimkin said Kyiv was seeking "critical" equipment to jam communications and counteract artillery usage.

"We don't need lethal weapons," said Ukraine's Pavlo Klimkin.

"What we need is to create a critical defense capability," he said.

The four ministers called for "strict implementation" of all ceasefire provisions.

In recent weeks, some US congress members have spoken in favor of arming Ukrainian forces, despite misgivings expressed by President Barack Obama.

Earlier this month, Britain promised to contribute up to 1,000 British troops to NATO's planned 5,000-strong rapid reaction force.

Baltic states worried

Last Friday, Lithuanian Foreign Minister Linas Linkevicius said Russia posed a threat to the west and south of Ukraine, including Moldova.

Six "command and control" centers for the force will be located in Bulgaria, Estonia, Latvia, Lithuania, Poland and Romania, with a corps headquarters in Szczecin, Poland.

All six countries were once in the Soviet Union's orbit.

ipj/gsw (AFP, Reuters, AP, dpa)