Wrightbus built London's new double decker buses
Wrightbus built London's new double decker buses AFP / Daniel LEAL-OLIVAS

Wrightbus, the manufacturers of London's iconic red double decker buses, entered administration on Wednesday, a spokesman for the company confirmed.

Wrightbus is best known for supplying New Routemaster buses to Transport for London (TFL) under the mayorship of Boris Johnson, who is now Britain's prime minister.

Based in Ballymena, Northern Ireland, the company is one of the province's largest employers.

The administration procedure is to be undertaken by Deloitte. The firm said 1,200 of 1,250 Wrightbus employees were made redundant Wednesday.

The Unite union has predicted a further 3,400 jobs will be endangered throughout the supply chain.

"It is bitterly disappointing for all concerned that despite extensive efforts over recent months it has not been possible to find a buyer who wanted to maintain the business as a going concern," said Deloitte joint administrator Michael Magnay.

"The joint administrators will explore all remaining options for the business and assets, and would encourage any parties with an interest to contact them," he added -- promising also "to support employees through this difficult time."

A spokesman for Wrightbus confirmed the business -- founded in 1946 -- had entered administration, but told AFP that a statement was not planned on Wednesday.

DUP MP Ian Paisley said the administrator now "has a week to find a buyer".

Wrightbus -- which based its business model on production of low-emissions vehicles -- has been seeking investment or a new owner as it struggles with cash problems.

"This is a workforce at the cutting edge of technological advancements in the design and supply of green public transport," said Jackie Pollock, regional secretary of the Unite trade union.

"We cannot afford to lose any more jobs or skills in this area."

As recently as 2016 the firm was awarded a £62 million ($77 million, 70 million euro) contract to produce the vehicles for the streets of the capital.

The iconic red "double decker" vehicles with a sleek updated design were dubbed "Boris buses", becoming a flagship project for the capital's then-leader.

But they were plagued with cost overrun and design issues -- including ventilation problems which saw passengers suffer in uncomfortable heat.

Pollock called on Johnson to intervene if no buyer is found.

"He has a chance today to do something decent," Pollock said.