HRT has expressed its surprise at Toyota's announcement that it has ended a planned technical collaboration with the Spanish team.
With HRT believed to have been on the verge of a deal that would have seen it develop a version of Toyota's planned 2010 car for its own challenger for next season, a statement on Monday said the deal was off.
Toyota cited that HRT had not met its contractual payment deadlines, and the announcement has seen doubt emerge about how the Spanish team will get a car ready for next season.
The outfit has so far remained silent about the implications of the Toyota announcement, but a short statement said: "Hispania Racing is very surprised about Toyota's press statement released this afternoon and this matter will be a subject of further clarification."
HRT began this season with a Dallara-built chassis but it terminated its relationship with the Italian racing car manufacturer early in the campaign.