Kiev- Ukraine's natural gas pipeline system needs an additional injection of fuel before deliveries to Europe can resume, a senior official in Kiev said Wednesday.

"We have asked for the assistance of the European Commission in resolving the problem of 'technical gas'," said Yury Prodan, Ukraine's Minister of Fuel and Energy.

"This is gas without which it is impossible to make transit shipments (to Europe)," he said.

London, Jan. 14 : Russia has been accused of trying to ''trick'' the European Union after gas supplies delivered through Ukraine were turned off again.

On Tuesday, Gazprom announced that normal service had been resumed of supplies to Ukraine. But within three hours EU officials announced that "little or no" gas was getting through.

Both Russia and Ukraine then blamed each other for a failure to reopen pipelines and the uneasy EU-brokered truce disintegrated as both sides traded accusations.

Sofia - Bulgarian Prime Minister Sergey Stanishev left Wednesday for a one-day trip to Moscow and Kiev and urgent talks about the Russian-Ukrainian gas row which has shoved much of the Balkans into a deep crisis.

In Moscow, Stanishev was due to meet both Prime Minister Vladimir Putin and President Dmitry Medvedev and the management of the Russian Gazprom, his cabinet said in Sofia.

Stanishev would then fly to Kiev, for talks with Ukrainian President Victor Yushchenko and Premier Yulia Timoshenko.

Brussels/Strasbourg, France  - The failure of Russia and Ukraine to deliver natural gas to the European Union despite repeated promises to do so is "unacceptable" and unjustified, the bloc's executive said Tuesday.

The European Commission believes that there is "no justification for these problems to continue" and Russia and Ukraine "have to realise that the situation is simply unacceptable," commission spokesman Johannes Laitenberger said.

The spokesman further warned that the credibility of both sides was now "on the line."

Moscow - Russia resumed supplies of gas to Europe on Tuesday as observer teams began measuring gas flows through Ukraine in an effort to mediate the ongoing standoff between Moscow and Kiev.

Ukraine's Naftogaz said it had received a fax from Gazprom informing it 76 million cubic metres of gas had been sent through the pipelines "at 10 am Moscow time" (0700 GMT), news agency Itar-Tass reported.

Brussels/Moscow/Kiev  - Russia should resume gas supplies to Europe via Ukraine on Tuesday, European Union officials and representatives from Russian state-owned gas monopolist Gazprom said Monday after a deal appeared to have been sealed in Brussels.

"If there aren't any obstacles ... gas transits can be renewed already tomorrow, at 8.00 am European time (0700 GMT)," Gazprom deputy chief Alexander Medvedev said during a visit to Brussels.