AstraZeneca has held talks with US rival Bristol Myers Squibb over a merger which could create a drugs giant worth more than £300 billion, according to reports.

The two pharmaceutical firms have held discussions over a potential tie-up in recent months, the Financial Times reported.

The move would mark one of the industry’s largest ever deals and create the world’s fourth largest pharmaceutical company.

Reports indicated that a deal could develop further in the near future but “may be delayed or fall apart”, according to sources.

AstraZeneca declined to comment.

Bristol Myers Squibb (BMS) has been contacted for comment.

Cambridge-based AstraZeneca is the UK’s second most valuable company, with a market value of around £196 billion.

New York-listed BMS focuses on cardiovascular and oncology treatments and is currently worth around £133 billion.

Any deal would be likely to face significant regulatory hurdles, amid significant scrutiny over the sector from competition and antitrust watchdogs.

A merger would be likely to be assessed by the Trump administration’s antitrust authorities, who have sought to increase domestic investment under President Donald Trump’s leadership.

A move comes amid efforts from AstraZeneca to grow its foothold in the US under boss Pascal Soriot.

The FTSE 100 firm completed a new additional listing on the New York Stock Exchange in June as a result, in a blow to the London markets.

Chris Beauchamp, chief market analyst at IG, said: “Companies saying one thing and doing another is a well-trodden path, and AstraZeneca joins in with the reports of a proposed alliance with Bristol Myers Squibb, having only said recently that it didn’t need M&A (mergers and acquisitions) to hit its targets.

“Though a rare example of a big UK firm buying a smaller US firm is something to warm the cockles of the British heart, it risks the departure of yet another national champion, and in any case the pair’s large cancer divisions is a major hurdle to a successful deal.”