Lee Johnston and Jackson Racing have parted company as practice for the Isle of Man TT looms on Saturday.

The Northern Ireland rider joined the team for the 2017 international road races after his former East Coast Racing outfit withdrew from the sport at the end of last season.

Johnston was due to ride Honda machinery in the Superbike and Supersport classes at the TT but a statement issued by the Preston-based team on Wednesday morning confirmed the split.

Aussie Josh Brookes will compete for Jackson Racing on a Honda CBR600RR in the Supersport races and the team is talking to another rider to take ride their second 600cc machine.

John McGuinness had also been due to ride for Jackson Racing in the Supersport class but has been ruled out of the TT through injury after a spill at the North West 200.

The statement from Jackson Racing said: "Jackson Racing have parted company with Lee and wish him all the best. This wasn't in the plan but that's racing.

"We had a positive test with Josh yesterday (Tuesday), the team worked well together and are now focusing on the Isle of Man TT. It's late in the day but we are talking to another rider and are hopeful we can have at least two Supersport machines on the grid.

"The Superbike will be prepared ready with the view that if the right rider comes along then we will run it.

Brookes will lead Norton's charge in the Superbike and Senior TT races alongside fellow countryman David Johnson.

Ulsterman Johnston is set to continue riding his BMW Superstock machine, which he rode at the Spring Cup and North West 200 meetings. He is also entered in the Lightweight race as part of Ryan Farquhar's KMR Kawasaki team.