Steve Plater in action during the Supersport race

Yamaha rider Steve Plater has been declared the winner of Monday's Supersport race despite finishing second to New Zealand's Bruce Anstey.

Officials excluded Anstey's Relentless TAS Suzuki machine because it did not comply with camshaft lift regulations.

So Plater from Lincolnshire, who was 21 seconds behind Anstey, was promoted to first place - his maiden TT victory.

Earlier, Cameron Donald from Australia won the Superstock race to complete an Isle of Man TT double.

The Relentless Suzuki rider, who won Saturday's Superbike race, triumphed by 15 seconds with John McGuinness second and Guy Martin in third.

They were followed by Ryan Farquhar, Conor Cummins and Adrian Archibald while the fastest lap was set by Donald at 127.54mph.

Anstey, the winner for the last four years, was forced to retire.

The New Zealander was challenging for a leaderboard position when he was forced out at the end of lap two.

Keith Amor and Gary Johnson also retired during the four-lap event.

"I can't believe it - the Superbike race was amazing but this was really special," said Donald.

"All the top riders were in the race and the bike worked so well. On lap two I got my head down and it really felt good.

"Once I crested the mountain on the last lap I knew it was mine.

"I am just happy to keep the Superstock crown for Suzuki and the Relentless team."

In the Supersport, Anstey's exclusion from the results meant John McGuinness was runner-up, Amor placed third, with Northern Ireland's Farquhar fourth, Michael Dunlop 10th and Archibald 12th.