london (Bloomberg) — Bermuda-based Frontline Ltd., the world's biggest operator of supertankers, said Bjorn Sjaastad, the chief executive officer of its management business, resigned for "family reasons," the third such departure in five years.

Frontline chairman John Fredriksen will assume the role until a replacement is found, the company said yesterday in a statement distributed by Hugin.

Sjaastad began the job in August 2006, taking over from Oscar Spieler, who quit the position after three years for a "less stressing" life. Spieler took over from Ola Lorentzon in September 2003.

Fredriksen has built up a 9.7-percent interest in US oil- tanker business Overseas Shipholding Group, according to a filing with the Securities and Exchange Commission on March 31.