A police investigation was launched today after a suspected arson attack on a cannabis factory.

The emergency services were called to the scene of the blaze, at a two-storey farm house on the Ballywatt Road outside Coleraine, shortly after midnight.

A PSNI spokesman confirmed that the fire appeared to have been started maliciously and that anti-Chinese racist graffiti had been daubed onto the building — which was completely gutted as a result of the blaze.

No-one was at home at the time of the fire and there were no arrests as a result of the discovery. After the fire was dealt with, a number of cannabis plants were discovered in the property.

Commenting on the overnight blaze outside Coleraine, a police spokesman said he could not discuss the nationality of the people believed to have been living in the property but said: “A number of cannabis plants, in the form of a ‘cannabis factory' were discovered in the building. The number of plants discovered is still being established and enquiries into the incident are ongoing.”

Earlier this year, police revealed they believe that illegal Chinese immigrants are running at least 30 cannabis factories across the province as 17 Chinese nationals appeared in court in Dungannon following a raid on three cannabis factories in Tyrone.

And in June, the PSNI also revealed that cannabis with a street value of over £8m has been seized from organised UK crime gangs who have moved their large scale cannabis manufacturing business into Northern Ireland.

The gangs have brought immigrants from South East Asia into the province to help in the cultivation of cannabis which is then being distributed across Northern Ireland and Britain.

Police said that in a major anti-drugs operation over the previous few months they seized cannabis plants with a street value of £7.3m, 113 kilos of herbal cannabis with a street value of £1.1m, £120,000 cash, searched 55 properties, made 56 arrests and charged 45 people, all of them from South East Asia.

A large number of cannabis factories being run from properties across the province were also shut down by the PSNI Drug Squad and uniformed officers.

Anyone with any information about the blaze or the cannabis factory is asked to contact detectives on 0845 600 8000 or to contact freephone Crimestoppers in complete confidence on telephone number 0800 555 111.