Channel 5's new owner Richard Desmond is understood to want to change the style of the broadcaster's news coverage, placing greater focus on "entertainment news".
Desmond is in talks with other potential news suppliers to end the relationship with Sky News, which has provided news bulletins to Channel 5 since 2005.
According to The Guardian, Sky News boss John Ryley told employees that Channel 5 wants to end the contract with Sky two years before its expiration in December 2012.
Last night, a Channel 5 spokesman confirmed that the broadcaster had put its news contact out to tender, but denied that it was looking to break the Sky contract early.
"We have put our news out to tender. Sky and other suppliers have been invited to come back with proposals and we will consider each in turn in due course," he said.
"In the meantime, Sky remains our current news supplier until the end of 2012 when the contract expires."
Desmond's Northern & Shell media firm is understood to have asked ITV News producer ITN, Question Time-maker Mentorn and US provider CNN to draw up alternative proposals to Sky's service.
In his email to staff, Ryley claimed that Channel 5 wants to "focus increasingly on entertainment news". He added: "Channel 5 recently informed Sky that they are already putting out to tender the contract to supply news after the current contract with Sky ends in December 2012 - yet the contract still has more than two years to run.
"At present, it is too early to say what the outcome of these discussions will be. I will keep you informed of developments and we will discuss what this means for employees in due course."
Desmond, who acquired Channel 5 for £103m in July, is expected to unveil a new schedule for the broadcaster in January next year as part of his restructure programme.