Rio Haryanto's hopes of returning to the grid this season have taken a dive as the Indonesian youngster loses main sponsor.

"This year there will not be a continuation of participation by Pertamina in F1," revealed a spokesperson for state-owned oil company Pertamina earlier today. "Of course we regret this very much, but we have already made maximal efforts for Rio and Indonesia."

Pertamina provided much of the funding that secured Haryanto his place with Manor in 2016, though the funding dried up after Germany. While Manor effectively gave the youngster a 'free' race in Hungary he was dropped after the summer break in favour of Esteban Ocon.

Haryanto, who had impressed during his time with Manor, had been linked with a return to the grid this season with both Sauber and his old team being mentioned.

Speaking to Reuters, his manager, Piers Hunnisett, insisted Rio still has hopes of a 2017 return.

"We are still working on a plan to keep Rio in Formula One," he said. "Obviously, we were hoping to move into a team like Sauber - that was the plan - but things are going to slow down a little bit."

"People in the Formula One world felt he did a good job and he deserves to be there," he added.

Indeed it now appears that having been snubbed by Mercedes the German manufacturer will pay for Pascal Wehrlein's berth at Sauber alongside Marcus Ericsson leaving the two Manor seats as the only remaining vacancies on the 2017 grid.

While the statement from Pertamina specifies F1, it is unclear if the company will continue to sponsor the Campos GP2 team which fielded Kiwi Mitch Evans and Indonesian Sean Gelael this season.

Having provided 5 of the 8 million euros Haryanto paid to Manor up until the point he lost his seat, despite being offered the opportunity to keep its branding on the cars opted to remove it. Manor had demanded 15 million euros from Haryanto for the whole season.