Boris Johnson: Pfizer takeover bid for AstraZeneca must not hit UK science

The Mayor said politicians could not be “aloof” from the deal, which the British company has so far resisted.

In particular, he argued that the Government should ensure that UK research and development received funding to cement its world-class status.

On his LBC radio show, Mr Johnson said: “When I look at something like AstraZeneca... the sheer percentage of its money that goes into R and D, I think it is of great importance to Britain.”

He added: “It would be very important to establish that Pfizer is genuinely committed to R and D in this country and that it won’t in any way damage what is the incredible success, particularly of London and the South-East...in dominating the European scene in life sciences and biotechnology.”

Pfizer has pledged to keep 20 per cent of the new company’s R and D spending in the UK.

But Labour leader Ed Miliband said Pfizer had a “pretty dubious” track record and accused David Cameron of being a “cheerleader” for the merger.

Conservative Chair Grant Shapps said there would be “tests” to ensure the deal “becomes a great Anglo-American project or it doesn’t happen”.