Honda has parted ways with consultant Gilles Simon on the eve of the Formula One season and at a time of increasing pressure for the Japanese manufacturer.

Engine expert Simon, who worked for Ferrari during its dominance of the early 2000s, joined Honda in 2013. His departure comes amid rumours of disagreements between Simon and Honda senior management about the direction the company needs to take with the development of its F1 engine.

A troubled first week of testing has led to fears of another uncompetitive season for McLaren, with two power unit changes required in the opening four days of pre-season. The second week of testing -- due to start on Tuesday -- will be crucial for Honda to rebuild faith in its ability to take McLaren back to the front of the grid.

Gilles Simon (right) played a key role in Ferrari's F1 programme in the 2000s Sutton Images

Simon's departure occurs at a time Honda is still investigating the engine failure which blighted the second day of last week's test.

A Honda spokesperson confirmed to ESPN: 'It is true that we are ending the contract with [Simon] within sometime of this year under each other's agreement. However, as it is a contract issue between him and Honda, we do not disclose further details.

"We appreciate very much for his great support and contribution to Honda's 4th era Formula One project."

The spokesperson did not confirm the reasons for his departure.

The new season begins with the Australian Grand Prix on March 26.