(CNN) — Al Qaeda in the Arabian Peninsula announced its responsibility for the presidential palace attack last Saturday in Yemen’s southern province of Hadramout.

The attack resulted in the death of 21 republican guards and the injury of nine others, according to the interior minister, and occurred just one hour after President Abdu Rabu Hadi was sworn in as Yemen’s next president, raising fears that al Qaeda was not weakened by the attacks against them.

The interior ministry said that an explosive laden vehicle drove through the presidential palace gate in the city of Mukalla. The attack was one of the deadliest terror attacks against security forces in recent years.

Ali Saeed Obaid, spokesperson for the military committee, the highest security authority in the country, told CNN that the attack will not affect the security of the country. “The presidential palace in Hadramout is on a mountaintop and not inside the city of Mukalla. That is why the civilian deaths are little to none,” he said.

He told CNN that al Qaeda stood behind the attack.

“Yemen is a country where such attacks take place, so this is not a surprise, but we will continue fighting terror until it is uprooted.”

Two senior security officials in Hadramout province told CNN hours after the attack on Saturday that it holds the hallmarks of al Qaeda.

“This was a message from al Qaeda to show everyone what they are capable of attacking and at the time they choose,” said one senior security official, who spoke on condition of anonymity.

Hadi stressed during his swearing in speech last Saturday that the new government will not be lenient in its fight against al Qaeda. “Continuation of the war against al Qaeda is a religious and national duty,” Hadi said.

Experts warned that al Qaeda is seeking to expand in territory benefiting from the absence of security forces in a number of rural areas.

“Al Qaeda expands in regions which lacks security presence, and that is why it succeeded in expanding in Yemen last year,” said Abdul Salam Mohammed, director of the Sanaa based Abaad Strategic Center.

“We expect them to continue attacking different targets. They know the new government will work to erase them so they have everything to lose,” he said.