A huge backlog of unpaid invoices to firms contracted by Birmingham City Council has been almost eradicated, the local authority claimed yesterday.

In early January there was a backlog of almost 30,000 invoices but that has now been slashed to just over 3,500. There is also a further 6,000 invoices that are being investigated further by the council to ensure they are legitimate.

The problems began in October when Service Birmingham, an arms-length company run by outsourcing firm Capita, installed the Voyager IT system - a wholly electronic method of paying invoices.

The new equipment is supposed to reduce the amount of staff time taken to process bills and help produce £280 million of savings for the council over 10 years. But it became clear almost immediately that the invoice scanning system was not working properly.

Finance staff were reduced to writing cheques by hand and the council was threatened with bailiffs by traders.

Since the system was installed more than 285,000 invoices have been paid to the council's 20,000 suppliers, totalling over £425 million.

Deputy city council leader Councillor Paul Tilsley recently visited the local authority's state-of-the-art new premises at Sutton New Road in Erdington where he thanked staff for their extra efforts.

Coun Tilsley (Lib Dem Sheldon) said: "The introduction of any new IT-based system is always challenging, and I have been delighted with the efforts that have been put in by city council staff - many of whom have worked at weekends - to ensure that Voyager works effectively and efficiently.

"The scale of transformation that we are undertaking is huge and Voyager will play a key role in helping the council and suppliers realise the massive financial and productivity benefits that it will reap in the years to come."