Libya's Defense Minister Mohammed al-Barghathi has resigned in protest over a siege by gunmen on the ministries of justice and foreign affairs, BBC News reported.

The militiamen had been demanding the introduction of a law banning Gaddafi-era officials from holding office. On Sunday, May 5, a week after the siege began, parliament passed the law.

"I will never be able to accept that politics [can] be practised by the power of weapons," the defense minister was quoted as saying.

The gunmen had said they would not leave the ministries before the passage of the bill banning those who had held positions under former Libyan leader Muammar Gaddafi from holding office.

"This is an assault against the democracy I have sworn to protect," said Barghathi, who was the commander of the Benghazi air force before he retired on a government pension in 1994.

The Political Isolation Law would apply to Barghathi when it comes into effect. The law could affect other senior members of the government, including Prime Minister Ali Zeidan.

Since the law was passed a number of gunmen have withdrawn from the ministries, but some groups of heavily armed fighters still remain.

The gunmen outside the justice ministry, said they are waiting to be replaced by official security forces.

Gaddafi was toppled and killed in an uprising in 2011, after ruling Libya for more than 40 years.