Conagra Brands Inc is in advanced talks to buy Pinnacle Foods Inc in a deal that could be announced as soon as this week, CNBC reported on Tuesday, citing sources familiar with the situation.

The news comes days after sources told Reuters that Pinnacle Foods, the owner of Birds Eye frozen foods and Mrs. Butterworth's syrups, had restarted talks about potentially selling itself to its larger peer.

A deal could still fall apart, the sources told CNBC.

Both Pinnacle and Conagra said they do not comment on market speculation.

Shares of Pinnacle, which rose as much as 6 percent immediately after the report, trimmed gains to trade up 2.5 percent. The company has a market capitalization of nearly $8 billion as of Monday's close.