Libya has announced that elections for a constituent assembly, the country's first national vote after four decades of dictatorship under toppled leader Moamer Gathafi, has been postponed to July 7.

The election had originally been slated to be held by June 19.

"The date for the elections will be July 7," the president of the electoral commission, Nuri al-Abbar, told a news conference in Tripoli Sunday, citing "logistical and technical" reasons for the delay.

The vote was postponed due to a delay in adopting a law to organise the elections, in order to give voters more time to register and to allow candidates who have been ruled out by the commission to appeal the decision, Abbar said.

He said that the commission started its duties on February 12 which gave it only "128 days to prepare the elections... a very short time, especially for a country that hasn't seen elections for almost half a century."

Abbar added that a note was sent on Sunday to the ruling National Transitional Council (NTC) to explain the decision to delay the vote.

A member of the electoral commission said the postponement had been decided in consultation with UN officials working with the commission who had "proposed a date during the first week in July."

More than 2.7 million Libyans, or around 80 percent of eligible voters, have registered to participate in the election.

The ruling National Transitional Council, having declared the country's "liberation" three days after the October 20 capture and killing of Gathafi, launched a roadmap to a new Libya with a 20-month countdown to elections.

A transitional government was to organise within eight months the election of a 200-member assembly, or "general national congress." The NTC is to step down once the congress holds its first session.

Dozens of political parties, which were banned under Gathafi's iron-grip rule as a "Western invention", have been founded in the months ahead of the Libyan elections.

A total of 120 seats on the assembly are reserved for independents, with the rest open to contest by political associations.

On June 3, the commission instructed the 4,000 candidates who hope to run in the polls not to launch campaigning before a date is announced.

On Friday, the European Union said it has deployed an election assessment team to Libya ahead of the polls, which EU foreign policy chief Catherine Ashton has described as a "crucial step in the ongoing transition."

Meanwhile a Libyan official said Sunday that an Australian lawyer detained after meeting Seif al-Islam, the detained son of slain dictator Gathafi, was being investigated for the crime of spying.

Australian Melinda Taylor was part of a four-person team from the International Criminal Court (ICC).

The ICC said in a statement on Saturday that all four had been detained after the meeting.

But Ahmed Jehani, Libya's envoy to the international tribunal, said that only two members of the team, Taylor and her Lebanese interpreter Helen Assaf, were in detention while two men, a Russian and a Spanish national, had stayed behind out of their own accord.

The ICC wants to try both Seif, 39, and his late father's spymaster, Abdullah Senussi, for crimes against humanity committed while trying to put down last year's bloody revolt.

But the new regime in Libya wants to put Seif on trial in a local court.

Gathafi was captured and killed by rebel forces on October 20 as his regime collapsed.

Australian Foreign Minister Bob Carr Monday said he had spoken to a senior Libyan minister over the detention, expressing hope that Taylor would be released soon.