Moscow, Sep 22 (IANS/RIA Novosti): In his first interview in weeks, Syrian President Bashar al-Assad has said rebels fighting his government "will not be victorious".

"The armed groups exercise terrorism against the state. They are not popular within society... they will not be victorious in the end," Assad told Egyptian weekly al-Ahram al-Arabi.

In his last major interview in August, Assad said it would take some time for his government to put down the uprising, which activists say has claimed around 23,000 lives since it began in March last year.

At least 54 people were killed when a government warplane attacked a gasoline station in northeastern Syria Thursday, al Jazeera TV reported.

In another development, Syrian government forces said they uncovered a mass grave in the capital Damascus, containing the remains of 25 people who were kidnapped by "armed terrorist groups", state news agency Sana reported.

Speaking from the presidential palace in Damascus, Assad said "change cannot be achieved through foreign intervention".

"Both sides of the equation are equal and political dialogue is the only solution. Violence, however, is not allowed... and the state will not stand with its hands tied in the face of those who bear arms against it," he said.

There would be no repetition of the Libyan experience in his country, he insisted.

But Assad also said the door remained open for dialogue with opposition groups.

"I welcome dialogue with the national opposition but those who choose arms have put themselves in confrontation with the Syrian Arab army," he said.

Diplomats from more than 60 countries agreed to step up economic pressure on the Assad government at a meeting in The Hague Thursday.