Sauber has confirmed it is yet to pay the February salaries of its staff in full.
According to Autosport, the delay is linked to ongoing talks with a potential title sponsor over a deal which has yet to be agreed. The report says staff have been treated equally and received an equal portion of their salary for last month.
When asked for comment, Sauber confirmed the news through a statement from boss Monisha Kaltenborn saying: "Part of the February salaries are still due, which I really regret."
Last year Sauber lodged an official complaint with Force India to the European Commission about F1's unequal revenue sharing and the decision-making Strategy Group. Kaltenborn is an advocate of introducing a budget cap to F1 to even the playing field for the sport's smaller teams, something the Strategy Group blocked when planned for 2015.
Sauber delayed the introduction of its 2016 car until the second week of winter testing in order to maximise development time. The team saw a noticeable drop off in performance last season as it struggled to bring upgrades to the C34 through the year.