Cosworth could be left with just a single Formula One customer in 2012, according to the latest reports in the specialist media.
New HRT consultant Luis Perez-Sala said last month that the Spanish team "will stay" with its current engine supplier next season because "we have a contract".
But Italy's Autosprint, and the Spanish sports daily AS, are reporting that HRT has been in talks with Renault about a two-year engine supply contract beginning in 2012.
Autosprint said the deal could also involve HRT using the rear end of the Lotus-Renault R31 that is raced this year by Vitaly Petrov and Bruno Senna, despite the Spanish team currently using a Williams gearbox.
If confirmed, the engine deal would make HRT Renault's fifth customer team for 2012, along with Red Bull, Renault, Team Lotus and Williams.
"If we have to supply more partners I would not be opposed to it," Renault's chief operating officer Carlos Tavares said this week. "As we have more partners we dilute our costs."
The speculation comes after it emerged at Monza that Cosworth's F1 boss Mark Gallagher is leaving the Northampton based engine maker.
If we have to supply more partners I would not be opposed to it
"What does it say for Cosworth's future?" The Times correspondent Kevin Eason wondered at the time.
It is also rumoured this week that Jorg Zander, the high-profile former Williams, BMW, Honda and Brawn designer, could be headed to HRT after meeting with team boss Colin Kolles at Monza last weekend.