*Magna CEO, representatives to meet UK union, govt this week

*Mandelson: willing to consider support to develop green car

British Business Secretary Peter Mandelson said on Monday he was prepared to discuss support for Vauxhall with parent Opel's new owners, Magna (MGa.TO), noting that representatives from the Canadian auto parts supplier were due in Britain this week.

A union representing workers at Vauxhall has said it feared at least 1,000 jobs could be cut under the planned takeover of General Motors [GM.UL] unit Opel by Magna with state-owned Russian bank Sberbank (SBER03.MM).

The head of the union had called for talks with Magna over the future of the two British plants, at Luton in southern England and Ellesmere Port in the northwest.

I hope (Magna's co-CEO Siegfried Wolf) he will have good discussions with union leaders, Mandelson told a group of reporters in Tokyo while on a visit to promote business and economic ties with Japan.

They're looking for hard information and strong assurance of the future viability of Vauxhall's plants.

Some countries that are home to Opel plants have urged the European Commission to ensure that the deal with Magna did not favour German workers because of 4.5 billion euros ($6.59 billion) in promised aid from Germany.

Mandelson said Magna representatives would also separately meet with the British government to seek financing for a deal.

Earlier this year Britain secured new investment from Toyota Motor Corp (7203.T) to build hybrid vehicles, and from Nissan Motor Co (7201.T) to produce batteries for electric cars.

Mandelson said support to Vauxhall to develop green car technology was an option.

We've given support in the past to Vauxhall for development of their green car and I'm prepared to consider that further, he said.

Speaking after meeting Nissan Senior Vice President Andy Palmer, Mandelson said he also hoped that Japan's No.3 automaker would consider Britain for the assembly of its zero-emission electric cars, due to be built somewhere in Europe from 2012. (Reporting by Chang-Ran Kim; Editing by Hugh Lawson)