Honda chief Yusuke Hasegawa has described the collapse of the Sauber-Honda deal as "very bad" for the Japanese manufacturer.
The Swiss team pulled the plug on the deal after Monisha Kaltenborn was replaced by Frederic Vasseur as team principal, with Sauber now opting to stay with current suppliers Ferrari.
Honda had been looking to work with a customer team in order to increase the amount of data they can gather on their much-maligned engines
"Of course it is very disappointing," Hasegawa said.
"It is a customer team program so it doesn't hurt our program very much, but we still expected to get the opportunity to get our engine running more.
"We would have got more data and been able to make comparisons, so it is very disappointing. More than that, on the practical side, we had to stop the preparation, so it is very bad."
Hasegawa revealed that he was not directly involved in negotiations with Sauber, but still felt the deal was in good shape up until the last minute.
He added: "I wasn't in the meetings, that was Yamamoto-san, Zander and I were in very good communication all the time.
"We both didn't believe that we would have to stop this collaboration until the final moment.
Honda talks with Toro Rosso have also collapsed, so McLaren could force Honda out of Formula 1 altogether should they decide to part ways ahead of the 2018 season.