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."

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.

Brussels  - The European Union has not tried hard enough to wean itself from its dependency on Russian gas, and now it faces a tough struggle to restore its security.

That was the verdict of industry experts on Monday as EU leaders waited to see whether the Kremlin's latest promise to have the gas flowing to Europe by the morning would bear fruit.

Prague  - The Czech presidency of the European Union Monday welcomed promise by Russian officials to resume EU-bound natural gas deliveries via Ukraine on Tuesday morning.

Brussels - European Union energy ministers were meeting in Brussels on Monday to discuss ways of dealing with the shortage of Russian gas arriving via Ukraine.

The supply is now expected to resume on Tuesday following a deal on gas monitors signed in Brussels by representatives of Gazprom, Russia's state-owned gas monopoly, and Ukraine's Naftogaz, whose pipelines are used by Moscow to deliver gas to Europe.

But the long-standing dispute between the two sides has already forced many European countries to dig into their reserves.

It has also sparked a row between Slovakia and neighbouring Austria over Bratislava's plans to meet its own shortfall by re-opening a Soviet-era nuclear reactor shut down by the EU for safety reasons.

Prague - An EU official Sunday signed a deal that allows international monitors to observe Russian gas flow via Ukraine, opening way for a renewal of gas deliveries to Europe, Czech officials said.

Speaking to reporters after returning from his mission in Russia and Ukraine, Czech Prime Minister Mirek Topolanek said that European Commissioner for Energy Andris Piebalgs inked the deal, which was signed earlier by Russian and Ukrainian vice-premiers.

Topolanek said that Russia reiterated its vow to open gas taps as soon as the deal is signed by all parties and observers are in their place as defined by the agreement.