Russia is highly likely to intervene in the Baltic states to test NATO's collective defence commitment, the former head of the Atlantic alliance was quoted as saying by Britain's Daily Telegraph on Friday.

"This is not about Ukraine. Putin wants to restore Russia to its former position as a great power," Anders Fogh Rasmussen told the daily.

"There is a high probability that he will intervene in the Baltics to test NATO's Article 5," he said, referring to the clause that commits NATO to respond collectively if a member is attacked.

"(Russian President Vladimir) Putin knows that if he crosses the red line and attacks a NATO ally, he will be defeated. Let us be quite clear about that. But he is a specialist in hybrid warfare," he said.

Rasmussen also called for increased defence spending in Europe, saying: "The situation is critical".

"We learned in the Libyan crisis that Europe is totally reliant on the Americans for air-refueling, drones and communications intelligence. We don't have air transport. It is really bad," he said.

NATO defence ministers on Thursday agreed to boost defences with six command centres in eastern Europe and a spearhead force of 5,000 troops, to counter what the alliance called Russian aggression in Ukraine.

The six centres that will help the deployment of the force will be in the three Baltic states -- Estonia, Latvia and Lithuania -- and in Bulgaria, Poland and Romania.

NATO is also set to boost its wider response force -- which would take weeks or months to deploy in a crisis -- from 13,000 to 30,000 troops.

German Chancellor Angela Merkel and French President Francois Hollande were due in Moscow Friday after getting Kiev's tentative backing for a crunch peace plan aimed at ending surging violence in Ukraine.

The frantic diplomacy to end the worst East-West crisis since the end of the Cold War came as US Secretary of State John Kerry also visited Kiev, with Washington mulling supplying Ukraine with arms to battle pro-Russian rebels.

Relations between Russia and Estonia have been particularly strained after an Estonian police officer was detained for allegedly engaging in a clandestine operation in Russia.

Estonia said the officer, Eston Kohver, was snatched from inside its territory at gunpoint and taken across the border in a blatant violation of its sovereignty.

Kiev says rocket fire hits Ukraine hotspot town after brief truce
Kiev (AFP) Feb 7, 2015 - Missile fire hit the battleground town of Debaltseve in east Ukraine Saturday a day after a brief truce allowed hundreds of civilians to flee, government officials said.

"In Debaltseve since 6:00 am this morning rebels have been firing Grad rockets," Kiev-loyal regional police chief Vyacheslav Abroskin said.

Ukraine's military had previously said that a temporary ceasefire that saw shelling of the beleaguered town halt for several hours Friday could be extended into Saturday.

Kiev's emergency rescue services said that 753 people, including 81 children were evacuated Friday from Debaltseve and surrounding towns after the government and rebels sent in buses to collect them.

A separatist military spokesman said Saturday that the insurgents were not planning to dispatch any more buses to evacuate civilians due to safety concerns.

Only some 40 people opted to head to the rebel side Friday.

Debaltseve -- mid-way between rebels centres Donetsk and Lugansk -- has been the focus of fierce fighting for over a week as insurgent fighters try to encircle government troops holding the strategic railway hub.

Amnesty International said earlier this week that most of the town's former population of 25,000 had fled, but that around 7,000 civilians remain behind.

Elsewhere around the region, rebels said that shelling overnight killed one local resident in insurgent bastion Donetsk.

Pro-Kiev authorities said that another civilian was killed when mortar fire hit his house in a village some eight kilometres (five miles) east of government-held port city Mariupol.