Some leading AstraZeneca shareholders were at odds over whether the British drugmaker made the right decision in rejecting Pfizer's final $118 billion bid to buy the company, news agencies report.

Schroder Investment Management, AstraZeneca's 12th-biggest shareholder with 2% of the company, urged the company's management to restart takeover talks with Pfizer. The UK arm of Fidelity Worldwide Investment, holder of the 18th largest stake in Astra, backed the British company's stance.

The division highlighted a split among investors following the collapse of a potential transaction, leaving many shareholders frustrated at missing out on a big windfall.

Schroders said it was disappointed with the quick rejection by the AstraZeneca board" of an improved £55-a-share offer on May 19 and the decision by Pfizer to draw a premature end to these negotiations by calling its latest proposal final.

"Given the increase in the offer, we would encourage the AstraZeneca management to recommence their engagement with Pfizer, and subsequently their shareholders," the fund manager said.

Schroders' comments echoed those of other shareholders, including Jupiter Asset Management, which were dismayed at AstraZeneca's rejection of Pfizer's offer on Monday.

The anger, however, was not universal.

"I think Astra did the right thing. I don't think that Pfizer was a suitable partner," said Dominic Rossi, London-based Fidelity's global chief investment officer for equities commenting on his company's stance. He argued that the deal was motivated by Pfizer's desire to cut taxes.

Anne Richards, chief investment officer at Aberdeen Asset Management, which holds 2.4% of the British drugmaker, also said Pfizer's offer "certainly wasn't a knock-out."

Veteran fund manager Neil Woodford, who controls AstraZeneca shares in funds he runs for wealth manager St James's Place, said he was "relieved that AstraZeneca appears to have retained its independence."

Strict British takeover rules mean the angry stalemate between AstraZeneca and Pfizer is almost certain to end with no deal, unless AstraZeneca's board does a U-turn and recommends Pfizer's final offer before the May 26 legal cut-off date

Pfizer may not privately or publicly even suggest its willingness to raise its "final" rejected bid, unless a third party makes a higher offer.

"This restriction that prevents further negotiation on value is a consequence of Pfizer's actions," AstraZeneca chairman Leif Johansson said in a statement.

The deal would create the world's biggest drugs group, if by some remote chance it goes through.