Security forces barred a top member of the banned Muslim Brotherhood, Egypt s strongest opposition group, from traveling to Qatar on Tuesday, security and Brotherhood sources said.

Essam El-Erian, who heads the Brotherhood s political department, said airport authorities told him they had been instructed by State Security officials to stop him from traveling.

El-Erian, who was recently released after more than six months in detention, was scheduled to travel to Qatar to attend a conference that brings together nationalist and Islamist activists from around the Arab World.

While his passport was initially stamped, airport officials told him they would carry out further checks, later informing him that he would not be allowed to leave the country.

El-Erian said he and other members of the Brotherhood had in the past successfully sued to have their names removed from the government s no-travel list, but were still often barred from travel.

Occasionally they ll let me through, and occasionally they ll stop me. But I no longer have the desire to seek their permission every time I want to travel … there s no legal basis for this, Erian said.

An Interior Ministry spokesman declined to comment.