The EU’s sanctions against Russia are to be expanded with more people added to the list subject to asset freezes and visa bans, EU foreign policy chief Catherine Ashton has said.

She said the action had been agreed in light of the latest events, as she also urged Russia to pull back its troops from the Ukrainian border.

Speaking after talks in Luxembourg with EU foreign ministers, Ms Ashton told reporters: “We condemn unreservedly the actions by armed individuals in the cities of eastern Ukraine.

“These attempts at destabilising Ukraine must stop. We strongly support the unity, sovereignty and territorial integrity of Ukraine.

“We call upon Russia to do so as well and pull back its troops from the Ukrainian border.

“Any further actions aimed at destabilising Ukraine have to stop.

“In light of the latest events we decided to expand the list of those subject to asset freezes and visa bans.

“Utmost restraint is crucial. We commend the Ukrainian authorities for pursuing the law and order operations in a measured manner and we encourage the government in Kiev to contribute further to reducing tensions.

“Free and fair presidential elections on May 25th are the best way to express the will of the citizens as is the process of constitutional reform.”

Earlier Ukraine’s acting president urged the United Nations to send peacekeeping troops to eastern Ukraine, where pro-Russian gunmen kept up their rampage of storming and occupying local government offices, police stations and airports.

The request came from a government that has proved powerless to rein in separatists in its eastern and southern regions, where insurgents have seized or barricaded government buildings in at least nine cities, demanding more autonomy from the new government in Kiev and closer ties with Russia.

The Kiev government and Western officials accuse Russia of instigating the unrest and of deploying armed Russian agents in civilian clothing to carry them out.

In a telephone call with UN secretary-general Ban Ki Moon, acting president Oleksandr Turchynov suggested that an “anti-terrorist operation” be conducted jointly by Ukrainian security forces and UN peacekeepers, according to the presidential website.

Peacekeepers, however, would have to be authorised by the UN Security Council, where Russia holds a veto. Mr Turchynov’s deadline for insurgents to give up their weapons and vacate their homemade barricades passed today without any visible action — instead, the violence continued.

A pro-Russian mob stormed a Ukrainian police station in Horlivka, another city near the Russian border. Later in the day, armed men in masks also seized control of a military airport outside the city of Slovyansk, also in the Donetsk region bordering Russia.

“The Russian Federation is sending special units to the east of our country, which seize administrative buildings with the use of weapons and are putting the lives of hundreds of thousands of our citizens in danger,” Mr Turchynov said, according to the presidential website.

The events echoed those in Crimea, which was annexed by Russia last month after key regional facilities were seized by Russian troops aided by local militiamen.

Dmitry Peskov, the spokesman for Russian president Vladimir Putin, was quoted by Russian news agencies as saying that Mr Putin has received “numerous appeals” from eastern Ukraine “asking him to help and interfere in one way or another”. Mr Peskov added that Mr Putin was “watching the developments in those regions with great concern” but would not elaborate.

The developments came three days ahead of a Geneva conference seeking ways to defuse tensions. Diplomats from the United States, Russia, the EU, Ukraine and Switzerland were expected at those one-day talks on Thursday.

Russia has warned the Kiev government not to use force against the armed protesters in the east, saying it could thwart the Geneva conference. Russian foreign minister Sergey Lavrov again denied today that Russian agents were operating in eastern Ukraine, saying it would contradict Moscow’s interests. He challenged Ukraine “not to be shy” about backing its claims of capturing Russian security officers with facts.

In Horlivka, however, one of the men directing the raid on the police headquarters introduced himself as a lieutenant colonel in the Russian army to a line of policemen who had switched sides. He did not give his full name.

In a video posted online, the man, dressed in an unmarked green camouflage uniform, urged the policemen to obey their new chief and to attach St George’s ribbons to their uniforms, which have become a symbol of the pro-Russian protesters. The identity of the man was not clear and could not be independently confirmed. Oleksandr Sapunov, who took part in storming the police building in Horlivka, said the insurgents were fighting against appointees of the new Kiev government, including the local police chief, and wanted to appoint their own leadership. “The people came to tell him that he is a puppet of the Kiev junta and they won’t accept him,” Mr Sapunov said.

Acting deputy interior minister Mykola Velichkovych acknowledged on Monday that some police officers in eastern regions were switching sides. “In the east we have seen numerous acts of sabotage from the side of police,” Mr Velichkovych told reporters.

Ever since Ukraine’s pro-Russian president Viktor Yanukovych fled to Russia in late February, Russia has demanded that Ukraine change its constitution to turn the country into a loose federal state.

Ukraine has said that its giant neighbour has no business telling it what type of government to have. After refusing demands for a referendum by separatists in the east, Mr Turchynov indicated today that holding a nationwide referendum on Ukraine’s status was a possibility. He said such a vote could be held on May 25th, along with the presidential election. Mr Turchynov expressed confidence that Ukrainians would vote against turning the country into a federation and against its break-up.

Agencies