A Tripoli government spokesman told Reuters on Friday that Libya's former spy chief Abdullah al-Senussi and a second national, Abu Agila Mas'ud, were also suspected of complicity in the 1988 airline bombing over Scotland.

Both are serving prison terms in Libya on charges unrelated to the bombing of the New York-bound Boeing 747.

Britain's former ambassador to Libya, Oliver Miles, said on Friday that Libyan authorities were unlikely to hand over al-Senoussi.

"He is too hot in Libya. He's the biggest fish in the pond," Miles said.

Scottish prosecutors on Thursday issued a formal letter seeking the cooperation of authorities in Libya which has two rival governments, four years after the revolt that ousted Moammar Gadhafi.

Libya not officially informed

The Tripoli government's media office director Jamal Zubia confirmed the names but said that the Libyan attorney general's office had not been officially informed.

The only person ever convicted was Abdel Baset al-Magrahi, who died in Libya in 2012 after being freed from a Scottish jail on the grounds that he had terminal cancer.

He had denied planting the bomb in a suitcase which was loaded onto a flight from Malta and then booked through via Frankfurt to the fated Pan Am flight out of London Heathrow.

Brotherly persistence

On Thursday, US and Scottish investigators said they hoped to visit Libya to interview the two new suspects also identified in an investigative documentary by US filmmaker Ken Dornstein.

His elder brother was one of the 270 people killed when the airliner was blown apart as it flew over the Scottish town of Lockerbie.

Dornstein from Sommerville, Massachusetts told the Associated Press that during a probe begun in 2011 he found out that among 10 suspects only three remained alive.

During a visit to a Libya jail, he tracked down Mas'ud who had been a "ghost" figure thought to have been traveling with al-Megrahi on the day of the bombing.

Dornstein said he traced Mas'ud via a passport number of a suspected explosives suspect linked by former East Germany's secret police to the 1986 bombing of La Belle disco in Berlin, which was popular with US personnel.

Relatives encouraged

US citizen Susan Cohen, whose daughter Theodora was 20 when she was killed in the attack, told Britain's ITV news that she was "delighted" by the investigative development.

"The governments have been dragging their feet and they should have been looking for other people involved, because it wasn't just Megrahi," Cohen said.

Jim Swire, a spokesman for the families of the British victims, also welcomed the news.

"If there is material that shows other people were involved then we want to know," Swire said. "We want to know who murdered our families."

Rapprochement

In 2003, Libya, then under Gadhafi, admitted responsibility for the bombing and later paid $2.7 billion (2.4 billion euros) in compensation to victims' families as part of a raft of measures aimed at a rapprochement with the West.

The Lockerbie downing took place two years after the United States conducted a series of air strikes against Libya that nearly killed Gadhafi.

ipj/msh (Reuters, AP, AFP. AP)