Sanaa: Yemeni authorities are investigating a tunnel dug near ex-president Ali Abdullah Saleh`s residence, the official news agency reported Tuesday, as his party charged it was an assassination plot. Former strongman Saleh ruled Yemen for 33 years before being forced out in February 2012 and replaced by his deputy, Abdrabuh Mansur Hadi, under a UN- and Gulf-sponsored deal. "The Supreme Security Committee received a complaint on Monday about a tunnel and excavation works near the residence of former president Ali Abdullah Saleh," Saba reported, quoting a committee official. "Security services immediately began legal measures and collecting evidence" from the site, on orders from President Hadi, it said. The 88-metre (290-foot) tunnel was connected to a hangar north of Saleh`s residence. A committee was formed to "identify the motives and parties" behind the tunnel, Saba said. The powerful General People`s Congress party, which is still headed by Saleh, said: "We were surprised to discover an organised terrorist act targeting the nation`s security, stability and unity." The tunnel was designed to "carry out a terrorist act" targeting Saleh`s "life, family, his security guards and leadership" of the party, the GPC said on its website. The party likened the alleged plot to a June 3, 2011 explosion in his presidential compound that wounded Saleh and killed 11 people. Critics accuse Saleh of impeding the political transition in the deeply tribal country, which is facing threats from al Qaeda, a northern Shiite rebellion and a southern secessionist movement.