* Swedish unions call for AstraZeneca to stay independent
* Opposition leader also worried about potential Pfizer deal
* AstraZeneca employs around 5,900 people in Sweden
By Sven Nordenstam
SODERTALJE, Sweden, May 14 (Reuters) - Unions representing AstraZeneca workers in Sweden called on Wednesday for the government to take a clear stand against Pfizer's offer for the firm, echoing British concerns that a deal could damage local scientific research.
AstraZeneca, formed in 1999 from the merger of Sweden's Astra and Britain's Zeneca, has rejected a $106 billion offer from U.S. drugmaker Pfizer, but a possible deal has raised concerns in both countries about the effect on jobs and competence in science and research.
"It is our belief that it is of over-riding public interest in the current situation to preserve a strong and independent AstraZeneca under British-Swedish leadership," the Swedish unions said in an open letter to the government.
"It would be deeply unfortunate if this branch of Swedish industrial culture ... were torn apart by short term interests where tax-planning rather than new medicines are the main drivers."
AstraZeneca employs around 5,900 people in Sweden and about 6,700 in Britain, out of a global workforce of around 51,500.
Swedish Finance Minister Anders Borg has already expressed concern about a possible deal, labelling it tax-driven and warning Britain that any promises from Pfizer to retain jobs should be treated with a pinch of salt.
Borg has said he has been in contact with the British government to express his scepticism about a deal.
Pfizer executives did not make commitments on the future for Swedish jobs or research in a conference call with Enterprise Minister Annie Loof last week, ministry spokeswoman Anna-Karin Nyman said.
Social Democratic party leader Stefan Lofven, whose party and its allies are leading in opinion polls with general elections only four months away, said he was worried about a possible takeover of AstraZeneca.
"If a big American player does this for tax purposes, one can ask oneself: what is the final result for us here in Sweden?," said Lofven, who stands to become prime minister if the centre-left opposition win the September vote.
The open letter did not make it clear what concrete steps the unions wanted the government to take and also called on shareholders to take a long-term view.
Concern about Sweden's life science industry has been mounting since AstraZeneca announced in early 2012 that it was shutting down research in Sodertalje, south of Stockholm, in a move that cut more than a 1,000 jobs. (Reporting by Sven Nordenstam; Writing by Simon Johnson; Editing by Niklas Pollard and Mark Potter)