The violence against protesters by President Bashar Assad’s government was “completely unacceptable” and increased international pressure was needed, Hague told Reuters after a meeting of EU foreign ministers in Poland.

Hague said a ban on any new purchases of Syrian oil by EU states from Saturday was a “very substantial” step given that it covered around 95 percent of Syrian exports and 25 percent of the revenue to the Syrian government.

Hague, however, acknowleged that Syria could export the oil elsewhere and declined to make clear whether Britain would back extending EU sanctions to a ban on investment by EU firms in Syria, as imposed by the US last month.

Analysts say the EU sanctions may have only a limited impact on Assad’s access to funds, but imposing an investment ban would require overcoming reluctance in some capitals, given that European firms like Anglo-Dutch Royal Dutch Shell and France’s Total are significant investors in Syria.

Hague said he believed the new EU steps would be taken seriously by the Syrian government.

“That does not of course preclude further measures being taken in the future,” he said. “We will continue that intensification over the coming months if this situation continues.”

“There will be ways of further increasing that pressure in the future, but I am satisfied that this is the right response at the moment. It is a very serious response and we would ask other countries in the world to join us in making it.”

Hague said the situation in Syria posed a great risk to stability in the region.

Any call for UN action would be aimed at increasing the pressure on Syrian authorities to end the violence but would not involve military intervention such as the West has pursued in Libya, he said.

Analysts say that the impact of international sanctions on Syria has been weakened by opposition by some global powers, including Russia and China, which have resisted a UN Security Council resolution laying out more measures.

Russian Foreign Minister Sergei Lavrov condemned European sanctions on Saturday, saying they “will lead to nothing good.”

“We have always said that unilateral sanctions will lead to nothing good. This ruins the partnership approach to any crisis,” he said on the sidelines of a summit of ex-Soviet states in the Tajik capital Dushanbe.

At informal EU talks in Sopot, Hague and French Foreign Minister Alain Juppe said more oil sanctions could be needed, but did not say what these might entail.

“If Bashar Assad is not listening and if there is no change in the regime, the sanctions will have to be intensified,” Juppe said.

Hague and Juppe both said the EU would continue to press for a tougher response at the UN, where some global powers, including Russia and China, have resisted a push led by the US and Europe for a UN Security Council resolution laying out more measures.

“We’re trying to convince India, Brazil and South Africa ... and to convince the Russians not to impose their veto,” Juppe said.

He said it was necessary to accelerate a change of regime in Syria and to help the opposition to organize.

As well as banning oil imports, the new EU sanctions target Syria’s Real Estate Bank, which provides mortgage finance, as well as Mada Transport and the Cham Investment Group, two arms of a Syrian investment firm which the EU says provides funds to Assad’s government.

Four Syrian businessmen were also added to a list of people affected by EU asset freezes and travel bans.

However, underscoring the EU divisions that have slowed the implementation of economic measures against Assad, Italy won an exemption on oil contracts agreed before the new sanctions round, which can be fulfilled until Nov. 15.

Other ministers, including Juppe and Finnish Foreign Minister Erkki Tuomioja, said it would have been better to implement the ban faster.

“I feel (it) is too late,” Tuomioja said.

“If we are serious, we should take any steps we take immediately.”