A military vehicle is stationed outside the al-Saleh mosque in Sanaa Monday.

SANAA: Yemeni forces have surrounded a sprawling mosque complex in the capital Sanaa amid fears that backers of ousted autocrat Ali Abdullah Saleh might use it as a launchpad to attack the presidential palace.

The operation, in its fourth day on Tuesday, is the most dramatic standoff yet between current President Abd-Rabbu Mansour Hadi and Saleh’s supporters since he was forced to step down in 2011 following mass protests after 33 years in power.

Dozens of troops in armored vehicles surrounded the mosque complex which straddles a major highway and is close to the presidential palace where Hadi conducts his day-to-day duties. Security officials believe the mosque could be used as a base for insurrectionists.

“There is information that there’s a tunnel leading to the presidential compound from the mosque, and weapons inside the basement,” a Yemeni security source told Reuters.

State news agency Saba quoted a source in the presidential guard saying on Monday: “After the arrival of information about the intention by some subversive elements to use the mosque to attack sensitive facilities nearby, guarding has been enhanced to protect the mosque and the surrounding area.”

Abdulwali Al-Qadi, the head of the mosque and a Saleh relative, denied that the building harbored any weapons.

“There’s no truth to these allegations,” he told Reuters. “There are no weapons in the basement, only books and Qur’ans.”

“The presidency wants us to hand over the mosque. They have no right to ask for that,” he said.

Government troops denied media access inside the site.

Elected to lead the impoverished Arabian nation’s political transition in 2012, Hadi has sought to chip away at the influence of Saleh and other officials and generals from the old government who diplomats say are seeking to regain power.

The mosque, whose six minarets tower over Sanaa, was named in Saleh’s honor in 2008 and cost tens of millions of dollars to build. Despite the upheaval in 2011, it has stayed in the hands of armed guards loyal to the ex-president.

Hadi reshuffled his Cabinet on Wednesday after street protests over deteriorating economic conditions.