SANAA — An aide to Yemen’s former president Ali Abdullah Saleh said on Thursday his security team had uncovered a plot to kill him with explosives planted in a tunnel running to a mosque inside his residential compound in Sanaa.

Yemen’s authorities said they were investigating.

Saleh, who stepped down in 2012 amid mass protests against his rule after more than three decades in office, remains an influential figure in the country and still has many enemies.

He has survived at least two assassination attempts, the latest in June 2011 when he sustained serious burns and several senior officials and aides were killed.

Abdullah al-Mughrabi, Saleh’s private secretary, said the plot came to light following a tip-off to his security guards from one of the people involved in digging the tunnel.

“Initial investigations showed that digging the tunnel began four months ago and its purpose was to assassinate the former president and his aides,” Mughrabi said.

He added that Saleh’s security went to inspect the tunnel and detained five people on the spot. Three of them were handed to Yemen’s top security team, a committee headed by the minister of interior.

An interior ministry official confirmed that three suspects had been turned over to the authorities by Saleh’s security team and said others were being sought for questioning.

Saleh retains the post of head of the General People’s Congress, the former ruling party and a main partner in the coalition government that was set up after he stepped aside.