By Alan Baldwin

SPIELBERG, Austria (Reuters) - Swiss-based Sauber believe they can see light at the end of the tunnel after months of struggling to pay staff salaries and stay in Formula One.

Team manager Beat Zehnder and Brazilian driver Felipe Nasr told reporters at the Austrian Grand Prix on Friday that the situation was improving with wages paid on time in June after delays in previous months.

There has also been talk in the paddock of a mystery investor likely to lead to a change in ownership, although team principal Monisha Kaltenborn has stayed tight-lipped about negotiations.

"Paying salaries definitely helps for the atmosphere in the team," said Zehnder after Friday practice at the Red Bull Ring.

"Paying the salaries, the outstanding salaries, is part of a comprehensive solution we were still working on.

"Obviously, there is a change in atmosphere because now everyone believes again that there is a future."

Sauber have been in Formula One since 1993 and finished overall runners-up in the championship in 2007 when they were owned by BMW.

The German carmaker's decision to pull out after the 2009 season, and hand the team back to founder Peter Sauber, left them in difficulties that they have battled ever since with varying degrees of success.

This season, with Nasr and Sweden's Marcus Ericsson, they have failed to score a point in eight races and have been unable to develop their car.

Tail-enders Manor, with their Mercedes power units, have also yet to score but are hoping to finish ahead of Ferrari-engined Sauber.

"The crucial thing so far was not to give up and I think we can be very proud of our team here on the track and at home that kept on pushing in our very limited areas," said Zehnder.

"There was always light at the end of the tunnel. But as you know, Switzerland has just opened the longest railway tunnel in the world. The light was always there, the tunnel was just massively long. The tunnel is getting shorter now.

"There should be a brighter future."

Zehnder said the team had been limited for financial reasons but hoped to have new "bits and pieces" for the next races in Britain and Germany before switching their focus to next season.

"We still have the aim to be in front of the Manors and possibly beat the Renaults but realistically, we have to concentrate, as a small team, fully for 2017," he said.

(Editing by Ed Osmond)