Canberra sent St George Illawarra's NRL season into a tailspin with a 30-6 routing at Canberra Stadium.

The Raiders were never headed as they surged to their fifth straight win on the back of a hat-trick of tries to centre Adrian Purtell, the Dragons' hot and cold offence frozen in the icy conditions in the nation's capital.

Impressive fullback William Zillman and Queensland Origin representative Neville Costigan were the other tryscorers for the home side, the Raiders putting a week of controversy following the suspension of Todd Carney behind them as they dismantled the visitors.

The loss was the Dragons' seventh in ten games with coach Nathan Brown sure to face another week of scrutiny, his plight not helped when Ben Hornby was forced from the field in a first half with a calf injury.

St George Illawarra were on the back foot from the outset with some precise kicking from Raiders halves Terry Campese and Michael Dobson forcing the Dragons into four goalline restarts in the opening 20 minutes.

But some resolute scrambling defence kept the home side at bay, the Raiders needing a 95 metre intercept try to Purtell to finally get on the board.

There was more than a touch of controversy over his second with Dragons centre Matt Cooper taken out in the lead-up, Raiders prop Ben Jones appearing to trip up Cooper to open up a gap for Zillman to create the four-pointer.

Having already denied Raiders winger Bronx Goodwin his first NRL try in the fifth minute for having his foot touch in-goal, video referee Phil Cooley this time went the way of the home side.

The Dragons needed to be first to score after the break if they were to be any chance, but some smart work out of dummy half by Lincoln Withers and then Alan Tongue put Zillman over for an 18-0 lead after 54 minutes.

Costigan then crossed on the hour to ensure the points for the home side, Purtell securing his hat-trick when he won the race for the ball after a long kick from Dobson caught the Dragons napping.

Copper ensured it wasn't all misery for the visitors with a consolation try in the dying stages, but the trip to Canberra will be one the Dragons will want to forget in a hurry.

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