Talks between General Electric and Vivendi over the future of NBC Universal have stalled, the New York Times reported on Friday night.

Citing people involved in the discussions, the newspaper said the two sides appear to be at least $500 million apart on how to value NBC Universal, which GE is hoping to sell to Comcast, the cable television company.

GE and Comcast were hoping to announce a deal as early as Monday, but the Times said its sources cautioned a deal is at least a week away.

Two people involved in the talks suggested it was possible no deal would be struck at all or that the French media company Vivendi might pursue an initial public offering of its 20-percent stake in NBC rather than sell it back to GE, the report said.

GE has been negotiating for weeks with Vivendi over buying its stake and then selling a majority interest in NBC to Comcast. About two weeks ago, GE reached an agreement in principle with Comcast that valued the television business at about $30 billion. Vivendi's stake is worth slightly more than $6 billion.

Earlier on Friday, a source familiar with the situation told Reuters that the sides were moving closer to a deal, with Vivendi agreeing to accept payment for just one-third of its stake until a related deal with Comcast closes.

(Reporting by Steve James; Editing by David Fox)