LONDON, Feb. 20 (Xinhua) -- A shortage of chickens that led to two thirds of KFC restaurants in Britain having to close was on the way to being resolved Tuesday.

Almost 600 out of 900 restaurants close when delivery problems led to them running out of their main ingredient, chickens.

The problem occurred days after KFC switched its delivery contract to a different company, with operational issues blamed for the delivery hiccup.

KFC restaurants posted notices in their windows to explain to customers the reason for the closures,

Media reports in Britain said that by 13:00 local time on Tuesday, 470 restaurants remained closed.

A KFC spokesperson said: "We anticipate the number of closures will reduce today [Tuesday] and over the coming days as our teams work flat out all hours to clear the backlog. Each day more deliveries are being made, however, we expect the disruption to some restaurants to continue over the remainder of the week, meaning some will be closed and others operating with a reduced menu or shortened hours."

Until mid-February, chicken was delivered to KFC's fast food outlets by specialist food distribution group Bidvest, and the delivery issue started after the contract was switched to DHL. Trade union GMB union, which represents many KFC workers, said it had tried to warn KFC that switching from Bidvest to DHL was a mistake.

GMB national officer Mick Rix said: "KFC are left with hundreds of restaurants closed while DHL try and run the whole operation out of one distribution center."

DHL said due to operational issues a number of deliveries in recent days have been incomplete or delayed.

"We are working with our partners to rectify the situation as a priority and apologise for any inconvenience," the company said in a statement.

Media in London reported disappointed customers voicing their frustrations on social media sites, some saying children were crying because they were missing out on their treats.

It even led to the Metropolitan Police in London posting a message saying, "Please do not contact us about the KFC crisis. It is not a police matter if your favorite eatery is not serving the menu you desire."