As staff put the finishing touches to a huge new superstore today, retail giant Sainsbury's said it had hired more than 400 people to work in it.

More than 1,500 jobs are expected to be created by new developments along the main Hardwick Road, on the eastern approaches to King's Lynn.

Hundreds more are being safeguarded by the new 70,000 sq ft Sainsbury's being built on part of the Pinguin frozen food factory site, the financial side of which has meant the firm could modernise its plant and remain in Lynn. The store chain said it expected the new store would open on Wednesday morning.

Manager Chris Pardoe, who previously managed the Sainsbury's at Longwater, on the outskirts of Norwich, said: 'We are excited about opening the doors to our customers and showing them all the new things Sainsbury's has to offer. It's also been built to reduce its impact on the environment.

'We're also looking forward to joining our store at the Vancouver Centre in becoming part of the local community and working closely with this year's chosen charity partner, Scotty's Little Soldiers.'

Alistair Beales, West Norfolk's portfolio holder for regeneration, said: 'Given the wider economic circumstances, it's very welcome that King's lynn can attract such investment and the 400 jobs are also very welcome.

Staff at the new store will raise funds for Scotty's, which was set up to support the children of servicemen and women killed in action by army widow Nikki Scott, whose husband Lee died in Afghanistan, in 2009.

Green features at the store include a ground source heat pump, under its car park, which will heat the building. It also recycles rainwater, has 1,000 solar panels on its roof and is built from sustainable timber.

A new link road being built between the new store and the A149 Lynn by-pass is also expected to open next week, once surfacing work is completed.

Tesco is also re-developing the former Campbell's food factory site, on the opposite side of Hardwick Road where the famous soup tower stood until it was demolished in February.

It has got the go-ahead for a larger store, along with a farm shop, hotel, bars and car showroom, which it says will create more than 1,000 jobs.

Tesco must also pay �830,000 to help King's Lynn town centre under the terms of the planning permission it was given in 2010, including improvements to the bus station, promotion of the town centre and enhancements to Saturday and Tuesday markets.