The man made the claim on Friday morning when he called up radio station Bombo Radyo Marbel, and said he and his companions carried the attack on Kimsan Plaza to force the owners to give their demand.
He said he and his companions were members of the Moro Islamic Liberation Front (MILF), a claim that was denied immediately by the spokesman of the MILF.
"We are asking P50,000 monthly from the store so we would not disrupt their operations," the purported Abu Sulaiman said in the radio interview.
The claim came as authorities said they eyed extortion as the motive behind the bomb attack that appeared to be intended to damage property than kill people.
MILF spokesman Eid Kabalu, on Friday, quickly disowned Sulaiman who is hunted by the military for allegedly masterminding the other previous bombings elsewhere in Southwestern Mindanao, and said that the MILF "does not engage in extortion activities".
"We have no Abu Sulaiman under the MILF's 3rd Brigade, 105th Base Command," he said. The guerrilla brigade has an operational area that includes areas in Southwestern Mindanao and portions of the Autonomous Region in Muslim Mindanao.
Government bomb experts said the explosion, which wounded four people, was caused by an incendiary bomb primarily intended to trigger fire.
This was the second time in three months that a bomb exploded in Tacurong City. A previous bomb exploded inside the public market on October 10 and injured four persons.
Sultan Kudarat Gov. Pax Mangudadatu condemned the attack but also chided the store management for apparently relaxing on its security measures.
Tacurong Fitmart, the largest department store in the area, has also received similar extortion letters from the group that carried the Kimsan attack, said local police chief Supt. Joel Limson. He did not identify the group, though.
The explosion came closely at heightened military security measures after a motorcycle laden with a bomb was found last Saturday near a checkpoint in Esperanza, Sultan Kudarat. (MindaNews)