Twin suicide bomb blasts killed at least 50 people and injured over 120 others on Monday afternoon in Pakistan's northwestern Mohmand tribal agency, officials and witnesses said.

Pakistani Taliban, the Tehrik-i-Taliban Pakistan (TTP), claimed the responsibility for the attacks, officials told Xinhua.

Two suicide bombers attacked the office of the Political Agent (PA), or the administration chief in Ghalanai, the headquarters of Mohmand Agency, a tribal region bordering Afghanistan, regional official Shams-ul-Islam said.

At the time of attacks, more than 200 tribal elders and officials were present in the office compound for a general meeting under peace committee for improving the law and order situation in the area, he said.

Both suicide bombers, wearing uniform of the local police Frontier Constabulary (FC), used motorcycles to reach the PA office in the regional headquarters.

On the way to office no police personal stopped them for checking as they were wearing the FC uniform. The first suicide bomber reached the big lawn of the compound and exploded himself among the people sitting on ground for meeting.

According to eyewitnesses, almost one minute after the first blast took place, another suicide bomber entered the building and tried to reach the blast site for a second attack as a lot of people were busy in rescue work. Police guard stopped him but he detonated his explosive jacket before reaching the target when the police arrested him.

Emergency had been declared in the headquarters hospital of the Ghalanai. Dr. Shaad Muhammad, the head of medical team in the hospital, told Xinhua that more than 100 people had been brought to hospital among whom 50 were dead and others injured.

Muhammad said that most of the injured were in critical condition and the severely injured will be shifted to Peshawar, capital of Khyber Pakhtunkhwa province.

Two important tribal elders, Malik Salim Khan and Malik Kachkol, reportedly have been killed while assistant administrator Roshan Khan was injured in the attacks, sources said.

Witnesses said that pro-government tribal elders, lobbying against Taliban militants, were holding a jirga council with the officials at the time of the attacks. They said that several members of the peace committee were among the victims.

After the second suicide attack, many rooms of the compound had also been collapsed down which also damaged the official data and injured many staff members.

Shortly after the attack, security forces reached the site, cordoned off the area and imposed curfew in the region.

Mohmand Political Agent Amjad Ali Khan told media that bombers used live bullets in their explosive materials which raised the damages. Khan thought that he might be the target but luckily, at the time of attack, he was not present in the office.

"We know who these terrorists are, they are now trying to survive in the area by these filthy acts, they had lost their war after we started military operation against them two and half years ago," Khan said.

It was the second major suicide attack in the area in the last five months. In July 2010, a Taliban suicide bomber killed nearly 100 people in Mohmand Agency when he detonated himself in the office of local administrator near a commercial area.

Mohmand Agency is located on the main road between Peshawar and Bajaur tribal region, once the stronghold of Taliban militants.

Officials believe that Taliban militants, who fled the Bajaur region after the military operation, took shelter in the mountainous areas of Mohmand Agency and now they are materializing their ill planes from mountains.

Pakistani Prime Minister Syed Yousuf Raza Gilani and President Asif Ali Zardari strongly condemned the suicide attacks and showed their commitment against the terrorism.

The prime minister declared it as an inhuman and brutal act of the militants who have no regard for any religion, the PM office said. Deploring the loss of precious lives in the blast, he ordered for provision of immediate and best medical facilities to the injured.