Yemeni public prosecution kicked off Wednesday an investigation into a formal complaint filed by outgoing President Ali Abdullah Saleh against a number of his opponents for last year's bomb attack on his presidential compound, official Saba news agency reported.

"Thirty suspects have been already investigated by the prosecution," Saba said without providing further details.

An official of the public prosecution's office told Xinhua that "several high-ranking dissident and opposition officials were suspected of being involved in the bomb attack and they will be summoned to the prosecution's office for investigation."

The official, who spoke on condition of anonymity, declined to reveal names of the accused.

The attack, which targeted the presidential palace in Sanaa on June 3, 2011, killed at least 13 high-ranking military and government officials and forced 87 others, including Saleh, to seek medical treatment in neighboring Saudi Arabia for months.

Saleh's aides have charged the opposition tribal leader Sadiq al-Ahmar and his brother Hameed, as well as a defected general, Ali Mohsen al-Ahmar, for masterminding the attack. However, the opposition coalition denied the accusation.