LONDON, United Kingdom - Libyan leader Muammar Gaddafi has built up a vast business empire which is the source of a bitter dispute between his children, diplomatic memos published in Wednesday's Financial Times claimed.

In a cable obtained by the WikiLeaks website and entitled "Gaddafi Incorporated," US embassy officials described how the long-serving ruler and his family had "direct access to lucrative business deals."

In the May 2006 document, diplomats wrote that Gaddafi's family had "strong interests in the oil and gas sector, telecommunications, infrastructure development, hotels, media distribution, and consumer goods distribution."

The children also drew "income streams" from the national oil company and oil service subsidiaries, giving them a stake in a sector which generates tens of billions in export dollars annually, the officials claimed.

The cable explained that Saif al-Islam, Gaddafi’s second son and heir apparent, had access to the oil industry through a subsidiary of his "One-Nine Group."

Gaddafi's daughter, Aisha Muammar, had close connections to the energy and construction sectors while Mohammed, the eldest son, had "major input over any telecom or internet service," the diplomats believed.

Third son Saadi was occupied "with his soccer teams, the Olympic Committee and his military career" but was involved in a three-way family fight over a Coca-Cola franchise, which the memo described as a "very twisted tale."

In 2009, Muammar Gaddafi agreed to invest 16 million euros (21.9 million dollars) in a hotel and water-bottling complex in the earthquake-ravaged Italian town of L'Aquila.

Activists said foreign regulators should trace and seize Gaddafi's assets.

"When a ruler is being questioned in his own country in the way Gaddafi is, people need to investigate immediately and freeze any assets they find until that investigation is complete," said Huguette Labelle, chair of the board of Transparency International.

"People have to do their homework and they have to do it fast," Labelle told the business daily.

When asked how much he believed the ruling family had hidden away, Alistair Newton, senior political analyst at Japanese bank Nomura, told Wednesday's Guardian newspaper that he "would be surprised if it didn't run into billions."

Another leaked cable, dated March 2009, detailed further examples of "internecine warfare" between the Gaddafi siblings which "provided local observers with enough dirt for a Libyan soap opera."

"Much of the (family) tension appears to stem from resentment of Saif al-Islam’s high-profile as the public face of the regime," the cable explained.

"Deeper tension about contradictions between Saif al-Islam’s proposed political-economic reforms...and the old school manner by which he has tried to monopolize the most lucrative economic sectors, also play an important role.

"The arrest of a number of Saif al-Islam allies since last summer...suggest that the current level of discord among Gaddafi’s children is acute," the cable concluded.