Alastair Seeley completed a Supersport double to bag his 17th victory at the North West 200 in dominant style.

There was controversy in the race as Lee Johnston was hit with a ten-second penalty after running on at the Juniper chicane as he disputed second place with Ian Hutchinson.

Johnston has submitted a protest over the decision, claiming that he was left with no choice as Hutchinson came up his inside and arguing that he didn't gain any unfair advantage.

Seeley timed his move to perfection as he moved into the lead on lap three at Metropole in Portrush and put the hammer down on the Gearlink Kawasaki, immediately pulling a gap over Hutchinson in second place on the Came BPT Yamaha.

The 36-year-old continued to stretch away and the chasing pack had no answer as he established a commanding lead, setting the fastest lap of the race at 117.522mph to open an advantage of six seconds.

Seeley said: "It's unreal and things just seem to be clicking away. Obviously coming here with a bit of confidence from BSB is good and I'm fit and healthy as well, which is a big thing.

"In the race I was sitting there and then I decided on lap three that I'd try and do something similar to Thursday night. I put the head down and I just tried to do a couple of qualifying laps and the gap crept up and up.

"I'm really happy for the team and everybody involved. Thanks to everybody waving the programmes around the course."

Hutchinson encountered misfortunate as he was forced out of second place with bike trouble, allowing Martin Jessopp to move into the runner-up spot on the Riders Motorcycles Triumph.

Johnston was running in second place on the road but finished sixth overall on the East Coast/Burdens Triumph after being hit with the time penalty.

Ballymoney's William Dunlop had led briefly on the IC Racing Caffrey Yamaha on lap three at Ballysally but the 30-year-old dropped out of the race with clutch trouble as he battled with Hutchinson and Johnston for third.

Newcomer Malachi Mitchell-Thomas on the Cookstown BE Honda and Peter Hickman became locked in a tussle for third place, gaining a few positions with Hutchy and Dunlop's demise and Johnston's time penalty.

With Seeley clear from Jessopp at the front, Bolton rider Mitchell-Thomas, making his debut at the North West, swapped places with Hickman on the Trooper Beer Kawasaki and it was the British Superbike star who edged the Bolton prospect for the final place on the podium.

Bradford's Dean Harrison finished fifth on the Silicone Engineering Kawasaki followed by the unlucky Johnston in sixth.

James Hillier (Quattro Plant Muc-Off Kawasaki), John McGuinness on the Jackson Racing Honda, Christian Elkin (Bob Wylie Triumph) and Paul Jordan (Honda) were the top ten.