Syria’s Muslim Brotherhood sought here on Monday to defuse fears that Islamist extremists were seizing Syrian territory, saying that a “united front” controlled land captured by the rebels.

“It is not true that extremists are in charge of liberated lands,” their leader Mohammad Riad Shakfa said at a press conference in Istanbul. “The land ... belongs to a united front of the opposition.”

Speaking in Arabic, he added: “As far as I know, there is no extremism in Syria.”

His comments came days after the jihadist Al-Nusra Front, one of the fiercest forces battling the Syrian regime, pledged fealty to Al-Qaeda, sounding alarm bells in the West and triggering concerns among the main opposition group, the Syrian National Coalition (SNC).

Western powers have been cautious in how they aid the opposition amid fears they could bolster Islamist extremists.

The powerful Muslim Brotherhood also denied it controlled the SNC, saying such claims were “manufactured” by Syrian President Bashar al-Assad as part of a “defamation campaign.”

“What we are up against is a campaign to defame us,” Shakfa said. “We make up less than 10 percent of the SNC and we have never influenced its decisions,” he added.

Shakfa was particularly referring to the election of Syria’s rebel Prime Minister Ghassan al-Hitto last month in a majority vote that had exposed rifts in the SNC.

“They claim Mr. Hitto was elected because he is our representative... We didn’t even know him before he was elected,” he said.

The brotherhood, a strong Islamist component of the fragmented Syrian opposition, supported Hitto because he was “more in tune with the wish of the majority,” according to Shakfa.

On Sunday, the SNC said Al-Nusra’s alleged merger with al-Qaeda would “only serve the goals of the Assad regime,” and called on the group “to stay within the ranks of the nationalistic Syrians.”