Ferguson had been negotiating a new contract with Nine for several weeks. He told his employers earlier today he did not want to stay.

It is understood that Ferguson will remain at Nine, and on air, until October when his contract expires.

Nine wanted to retain Ferguson and sources say CEO David Gyngell had made a "significant" offer to keep him.

The decision is complicated by the fact that Nine has just launched This Afternoon, a new pre-news program, with Ferguson as one of its three presenters.

Since its launch on Monday This Afternoon has attracted criticism for its Sunrise-like set, the awkward chemistry of its three hosts and has struggled to hold an audience.

It made a soft debut to 321,000 viewers nationally on Monday, slipping to 314,000 on Tuesday and 238,000 on Wednesday.

The pre-6pm news timeslot is dominated by Seven's afternoon newscast and Ten's one-hour bulletin.

There are industry rumours Ferguson will sign with the Seven Network to read weekend news.

Seven is not commenting, though sources say a statement may be released later today.

Ferguson is one of several names who has been whispered previously as part of a broader succession plan for Seven's top-tier newsreading team: the soon-to-retire 6pm newscaster Ian Ross and Chris Bath, who is his anointed successor.

Nine dumped Ferguson as the presenter of Nine's 6pm bulletin in January, replacing him with 60 Minutes journalist Peter Overton, a move orchestrated by the now departed news and current affairs chief John Westacott.

The move, which surprised many, resulted in a sharp drop in Nine's 6pm news ratings, which the network is still struggling to recover from.

Overton had lobbied heavily for the post since the retirement of legendary newsreader Brian Henderson in 2002, but was considered too inexperienced for the role, which went first to Jim Waley and later to Ferguson.

Though he remained on cordial terms with Nine's management, Ferguson was said to have found his demotion at Nine hurtful, particularly given the all-important 6pm news had gained so much ground under his watch.

His departure will be interpreted as a stunning blow to This Afternoon, which features Ferguson, Andrew Daddo and Katrina Blowers.

Ferguson is considered one of the most well-credentialed news presenters in Australia, having worked as a foreign correspondent for Nine covering major international news stories, including the death of Princess Diana.