Ukrainian forces killed up to five pro-Moscow rebels yesterday as they closed in on the separatists’ military stronghold in the east and Russia launched army drills near the border in response, raising fears its troops would go in.

Under an international accord signed in Geneva last week, illegal armed groups in Ukraine, including the rebels occupying about a dozen public buildings in the largely Russian-speaking east, are supposed to disarm and go home.

But they have shown no signs of doing so and yesterday the Ukrainian Interior Ministry said its forces backed by the army had removed three checkpoints manned by armed groups in the separatist-controlled city of Slaviansk.

“During the armed clash up to five terrorists were eliminated,” it said in a statement, adding that one person had been wounded on the side of the government forces.

Kremlin maintains it has the right to protect Russian speakers if they come under threat

A rebel spokeswoman in Slaviansk said two fighters had died in a clash in the same area, northeast of the city centre.

The Kremlin has built up forces on Ukraine’s border – estimated by Nato officials at up to 40,000 troops – and maintains it has the right to protect Russian speakers if they come under threat, a reason it gave for annexing the Crimean peninsula from Ukraine last month.

In St Petersburg, Russian President Vladimir Putin said that if the authorities in Kiev had used the army in eastern Ukraine, this would be a very serious crime against its own people.

“It is just a punitive operation and it will of course incur consequences for the people making these decisions, including [an effect] on our interstate relations,” Putin said in a televised meeting with regional media.

Reuters journalists saw a Ukrainian detachment with five armoured personnel carriers take over a checkpoint on a road north of Slaviansk in the late morning after it was abandoned by separatists who set tyres alight to cover their retreat.

However, two hours later the troops pulled back and it was unclear if Kiev would risk storming Slaviansk, a city of 130,000 that has become the military stronghold of a movement seeking annexation by Moscow of the industrialised eastern Ukraine.

At another checkpoint set up by the Ukrainian military, a soldier said they were there to instil law and order.

“Those separatists, they violated the Constitution, they are torturing the country, they violated laws, they do not recognise the authority of police so the army had to move in and we will finish what we have started so help me God,” he said.

The Geneva agreement, signed by Russia, the United States, Ukraine and the European Union, was already in trouble as Kiev launched its offensive to regain control of the east. East and West have put the onus on each other to ensure the accord is implemented on the ground. US President Barack Obama said earlier he was poised to impose new sanctions on Moscow if it did not act fast to end the armed stand-off.

Putin said sanctions were “dishonourable” and destroyed the global economy but that so far the damage had not been critical. Russia’s Defence Minister said it had begun military drills near the border with Ukraine, where it has deployed tens of thousands of troops, in response to “Ukraine’s military machine” and Nato exercises in eastern Europe.

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