A "world renowned" art collection is gathering dust because there is not enough room to display it.

Just 20 per cent of Blackburn Museum's artefacts, thought to be worth millions of pounds, are on display to the public.

That leaves the remaining 80 per cent in storage and out of sight.

Supporters of the museum are now calling on the council to make more space available.

Joy Heffernan, chairman of Friends of Blackburn Museum, said she was "staggered" when she saw the items hidden away.

She said: "They have got lots of paintings and sculptures.

"They are stored in rooms at the back and in the basement and in nooks and crannies.

"It belongs to the people of Blackburn. We are pushing for more space to show off what we've got."

She said she hoped plans to bid for about £4million of lottery funding to extend the museum would come to fruition.

The museum owns about one million artefacts, and donations are having to be turned down because of the lack of room.

But just 25 of a rare set of 1,000 Japanese wood block prints can be shown at the same time.

The set, thought to be the best in the country, was acquired in 1938 from the Blackburn cotton magnate Thomas Boys Lewis.

The museum also owns four watercolours by legendary landscape artist JMW Turner, but these are normally kept away from the public gaze because they could be damaged by the light.

Museum bosses rotate most of the items on display, but admit it would be at least 10 years before all items see the light of day.

The museum's former curator Mike Millward, who was in charge from 1976 to 1995, said the decision by the previous Labour administration to close the Lewis Textile museum in Exchange Street in a cost-saving drive meant space was at a premium.

He said: "Museums always have more than they can display, and I wouldn't want it any other way.

"But I have made this point to the council - when they closed the textile museum they closed a very useful gallery.

"Now the textile museum is downstairs in the museum, but what's it taken the place of? Another gallery?

"It's a great shame. Blackburn has a very good collection - it's world renowned.

"There is a lot of things that are very spectacular."

County council museums officer Edmund Southworth said: "It's a fact museums have more behind the scenes at any one time than they have on display, and there are good reasons for that."

Blackburn with Darwen museum's current curator Paul Flintoff said: "It's a dilemma that every museum faces.

"Your job is as much to preserve items as it is to display them."

Coun Michael Law-Riding, executive member for leisure and culture, said appointments could be made to view items not on display.

He added: "We feel that the real value of the art collection is its ability to inspire and educate which can be measured by the 40,000 visitors and students who visit the museum and gallery each year."

Council bosses have refused to reveal the total value of the museum's collection, citing "security" concerns.