NFI Group Inc officially announced today it had acquired the company in a move that will see the parties “share best practice and technology development”.
Unite wants to ensure “future job security” is safeguarded as part of the agreement.
ADL’s Camelon depot directly employs around 1000 workers who are part of its 2500 global workforce.
Its Scottish operation consists of the Camelon manufacturing site and the Larbert corporate headquarters.
ADL was saved from potential collapse in 2010 after hundreds of Unite members agreed to work a three-day week to stave off 260 redundancies in the aftermath of the global financial crash.
The firm had previously shed almost 100 jobs in the spring of 2009.
Following extensive lobbying by Unite, a Green Bus fund was set up in 2010, raising an initial £4.4m which resulted in the vast majority of orders being placed for hybrid buses at ADL.
More than £16 million has since been allocated to the fund, 360-plus low carbon emission buses joining its Scottish fleet.
Pat Rafferty, Unite Scottish secretary, said: “Unite is calling for an urgent meeting with the new owners of Alexander Dennis to seek assurances on future job security.
“It’s important to state that we have had productive industrial relations following the vital role Unite, and the workforce, played in keeping the company in business nine years ago.
“Alexander Dennis is now a world leader in manufacturing and a Scottish success story.
“Unite wants this success story to continue but it is vital NFI assures the workforce of its future business plan going forward.”