The Swiss team has run Ferrari power since 2010 but Sauber has been working on finding a new partner.

Talks with Honda have been ongoing for some time but accelerated in March, and the finishing touches are now being put to what will be a long-term arrangement.

Sauber is bracing itself for a challenging season with year-old Ferrari engines, but a switch to Honda next term will see the team return to using the latest spec.

The deal is the latest step in Sauber's rebuilding plan, after new investors came onboard last July to save the team and solidify its future in F1.

When Honda returned to F1 in 2015 with McLaren, an agreement was made whereby both parties had to approve if Honda took on a second team.

The regulations subsequently changed, with the FIA now able to compel the manufacturer with the fewest customers to supply a team that needs an engine.

Honda was not keen, particularly given its struggles with performance and reliability, but would do so if asked because of its duty to F1.

When the situation on and off track improved last year, Honda turned its attention to the possibility of taking on a second team.

Last summer, it expanded its Milton Keynes base to provide the space to accommodate another supply and talks with interested parties beginning soon after.

Sauber emerged as the frontrunner, particularly given it was growing increasingly frustrated with supplier Ferrari regarding performance and unreliability.

An announcement is expected in the coming days with engine manufacturers required to notify the FIA of who it intends to supply for 2018 by May 6.

McLaren boss Eric Boullier admitted last week that, given Honda's problems this year, the Japanese manufacturer could benefit from having more teams running its engines.

"I think in this specific case it's better," he said of the lack of testing miles. "I think more teams is better and more engine running is better. But there is a price to pay for that, which is deviating more resources into building more engines.

"Whatever happens, we are partners, so at some stage there will be a second team supply question, and I think we'll have to support this. But we want to make sure it's not detrimental to our partnership."

Additional reporting by Jonathan Noble