THE building site of Manchester's new children's hospital has been evacuated after a sixth suspected arson.

Workers discovered the blaze - reported to be the sixth since last Tuesday - on the second floor of the part-built unit this morning.

Fire-fighters were called to the site on Upper Brook Street, next to the Manchester Royal Infirmary, at 11.30pm.

It was the second fire today and the sixth since last Tuesday according to workers.

Fire-fighters and police are investigating the blaze along with a blaze last Tuesday and one on Monday which caused £1/2m of damage.

About 1,000 people are working on Europe's biggest hospital building project.

It will replace Royal Manchester Children's Hospital, in Pendlebury, and Booth Hall Children's Hospital in Crumpsall. New wards will be built for the MRI, St Mary's Hospital for Women and Children and the Eye Hospital.

Workers say the site was closed yesterday morning after the latest fire on the second floor, while all staff went to a health and safety briefing.

One man, who asked not to be named, said: "It is not a good atmosphere while this is going on - we're all aware there could easily be a major blaze. We've been told to look out for anyone acting suspiciously."

A spokesman for Greater Manchester Fire Service said: "We have attended two fires at this site, both started in a quantity of cardboard boxes. Both may have been deliberate fires and we are working with security on the site and will reinforce the no smoking policy."

Building firm Bovis Lend Lease, which is leading the project, said: "We can confirm there was a fire on Monday within the new hospital development, with everyone safely evacuated from the site."

It is not thought the fires will cause a delay in building work and the damage is expected to be covered by insurance.

A spokeswoman for Greater Manchester Police said: "We are working with the Fire Service and staff based at the site to investigate the circumstances surrounding the fires."