TRIPOLI — Gunmen kidnapped a leading member of a Libyan Islamist party affiliated with the Muslim Brotherhood, a party spokesman said on Monday, in a further sign of lawlessness crippling the oil-producing country.

No group claimed responsibility for the abduction on Sunday night of Mohammed Hraizi. But kidnappings for political coercion have become increasingly common in Libya, where Islamists, brigades of former rebels, tribes and factional militias all compete for influence over the weak central government.

“Dr. Hraizi was kidnapped last night on the airport road in Tripoli after evening prayers,” Hussam Al-Naili of the Justice and Construction Party (JCP) told Reuters.

He quoted eyewitnesses as saying the abductors were driving military police vehicles and the JCP had not yet been contacted by the gang.

The JCP is the main Islamist party in Libya and vies for power with the more nationalist and secular National Forces Alliances.

Many Libyans hope that a new legislature, the House of Representatives, elected in a weakly attended ballot this month, may be able to guide the state out of its current crisis and away from the influence of heavily armed militias.

Libya has struggled for three years with bands of former rebels who helped topple dictator Muammar Gadhafi with the support of NATO air strikes, and they remain influential players in Libya’s disordered democracy.