Dozens of extra firefighters were drafted in today as efforts to extinguish a huge fire at a metal scrapyard were stepped up.

Dozens of extra firefighters were drafted in today as efforts to extinguish a huge fire at a metal scrapyard were stepped up.

Around 80 firefighters are now tackling the blaze at the scrap metal merchants in Renfrew which broke out amid a huge mountain of twisted metal yesterday afternoon.

It is still roaring and is expected to burn for at least another day.

The blaze sent huge smoke clouds billowing down the River Clyde and over the centre of Glasgow, several miles away.

The wind direction has now changed, and a 300ft high plume, stretching between five and 10 miles, has gathered to the south-west of Renfrew.

The surrounding area has not been evacuated and no-one has been injured.

Fire chiefs said specialists were monitoring the air quality and the Scottish Environment Protection Agency (Sepa) had been informed.

Strathclyde Fire and Rescue Service described the fire at the Christie & Son Meadowside Street yard as a "mountain of mangled and twisted scrap metal".

Group commander Andy McCafferty said: "This is a very deep-seated fire which is going to take a considerable time to extinguish.

"A technical support team of chemists have been here throughout the night but the smoke pall is rising quite substantially, so should not affect any residential properties.

"However, if anyone is worried, our advice would be to keep their windows and doors closed."

Diggers at the site have been drafted in to rip huge chunks of scrap from the blazing mound, in a bid to help the firefighters get to it.

Hose-reel jets and ground monitors are also in use and seven appliances are at the scene.

A tug boat from Greenock is also being used to give fire crews easier access to water supplies as they fight the blaze.

A fire service spokeswoman said their efforts had also been affected by the "hazardous nature" of some of the materials ablaze.

The fire caused incoming aircraft at nearby Glasgow Airport to use a slightly different approach for around 30 minutes last night.

A BAA spokesman said this was due to the potential for thick black smoke gathering on the runway.

He added that the measure had been taken as a precaution.

"There was no real impact in terms of operations but we are very aware of the situation and are continuing to monitor it," he said.

A spokeswoman from Christie & Son said they had no comment to make.