Ministers clash on US takeover plan as Labour's national interest test proposals met with accusations of being 'anti-business'

The coalition was struggling on Sunday night to maintain a united front on the proposed £63bn takeover of the British pharmaceutical group AstraZeneca by its giant US rival Pfizer as ministers gave conflicting responses to a proposal by Ed Miliband to toughen up the rules to protect key British companies.

As AstraZeneca stepped up its campaign against Pfizer, Vince Cable, the business secretary, gave a guarded welcome to by the Labour leader's proposal to expand the public interest test to protect Britain's "strategic" science base.

But Conservative party chairman Grant Shapps said Miliband's proposal was "anti-business, anti-jobs and anti-jobs security".

The mixed signals from the coalition came after Miliband said no other country in the world would simply wave through a takeover of such strategic national importance.

He also accused David Cameron of acting as a cheerleader for the US group's proposed bid for its British rival after the prime minister praised the US giant for delivering "robust" assurances.

Cameron spoke out after Ian Read, Pfizer's Scottish-born chief executive, promised to complete a "substantial" Pfizer research and development facility in Cambridge and to employ at least 20% of the combined company's total R&D workforce in the UK.

Miliband, however, said Pfizer had a "pretty dubious record" on takeovers and wrote to the prime minister calling for a change in the law to create a new public interest test to cover strategic economic interests.

Under the Enterprise Act, the business secretary can intervene in a proposed takeover on grounds of public interest if there is a threat to national security, media plurality or financial stability.

In his letter to the prime minister, Miliband called for a "more substantive assessment" of whether the takeover of "strategic elements of our science base" were in the national economic interest.

The Labour leader also called for an independent assessment of the impact a Pfizer takeover would have on Britain's long-term science and industrial base.

He told the Andrew Marr Show on BBC1: "David Cameron is in totally the wrong place on this issue. He has become a cheerleader for Pfizer's takeover when instead he should be championing the long-term agenda for high-quality jobs in this country which AstraZeneca provides.

"No other country in the world would be waving this bid through, nodding it through on the basis of pretty weak assurances from Pfizer, who have a pretty dubious record when it comes to their record in this country and other takeovers," said Miliband.

"The prime minister, rather than being that cheerleader for this takeover with paper-thin assurances, should be actually championing British jobs and a British success story that is AstraZeneca – investing in research and development, a crucial part of our science base."

Cable indicated that he would be taking Miliband's idea seriously. The business secretary told the BBC: "We have obviously been looking at the options around the public interest test and other factors." Asked whether there were plans to review the public interest test, he said: "Obviously we are looking at this option amongst others."

But Shapps told Sunday Politics on BBC1: "Miliband's approach is to simply be anti-business, anti-jobs, and anti-job security that families in this country want."

Shapps later told The World This Weekend on BBC Radio 4: "Playing politics with it, coming in and writing that kind of letter that suggests you want to introduce some new additional tests – the sort of tests they completely failed to use when Labour messed up the Kraft/Cadbury takeover – is really disingenuous. I don't often say this but, on this occasion, Miliband has overstepped the mark."

The contrasting remarks by Cable and Shapps highlighted different views within the government over the proposed deal. Cable is insisting that, from the moment the takeover emerged, he had been attempting to protect British jobs and AstraZeneca's research and development facilities.

The initial response of Conservative ministers was to hail the planned takeover as a sign of Britain's competitive corporate tax regime.

Cable is expected to stop short of introducing emergency legislation to change the law in line with Miliband's proposal. It is understood that existing legislation gives him enough power to intervene to protect Britain's science base.

Shapps indicated that the Tories had changed tack and were now stressing the importance of protecting Britain's science base: "We are going to have tests which ensure this get together becomes a great Anglo-American project or it doesn't happen."

The Tory chairman told the BBC: "The government's assessment of this is that we will be fighting for British jobs and British science, the research and development and the rest of it ... Everybody knows there are good and bad takeovers, good and bad mergers.

"This could be a great Anglo-American company but we have to make sure that both sides are approaching it in good faith and it is in Britain's interests, meaning for British jobs and British science."

Shapps rejected Miliband's claim about the prime minister. He said: "The idea that we are cheerleading for one or the other side of this is completely insane. It symbolises Ed Miliband playing politics literally with people's jobs in this case."

An AstraZeneca spokesman said: "AstraZeneca has a deeply rooted history in the UK and we have reiterated our long-term commitment through our continued investments in research, development and manufacturing, which we believe will deliver value for our company and for society for years to come."