"Yes, that's true. Some of the February salaries are still outstanding. I deeply regret that," Kaltenborn was quoted as saying by Blick.

The Swiss squad finished the 2014 season with zero points behind Marussia, a situation that meant a financial hit for the team.

Sauber recovered from the disastrous year in 2015, going on to finish in eighth place in the standings with 36 points.

The Hinwil-based team, however, was understood to have to pay 15 million euros to Giedo van der Garde following their legal battle last year.

Kaltenborn admitted the situation was "tense", but was confident it will be solved soon.

"It's tense. Right now, it's the most cost-intensive time of the year. Concerning the transfer of a big amount of money from a sponsor from abroad, some problems occurred.

"We will solve this within a short time.

"We will get on top of the current issues and we will get out of this awkward situation. We will fight and we will get out of it, just like we did in the years past."

Sauber was the only one of the current teams to not run its 2016 car in the first test at Barcelona, its C35 making its debut in the second test.