OM sent a third plea to shareholders calling for their support for its audacious takeover approach, and giving them until November 10 to make up their minds. Failure to secure a majority of votes by that date will result in the offer lapsing under British takeover rules, which give a predator company 60 days to make its case.

OM's initial offer unveiled in August shook the City of London, with the financial community outraged that a small Swedish minnow could prey on a venerable national institution.

OM admitted that its first offer attracted only one per cent of shareholder support, and so bumped up the 800-million-pound offer by some 30 per cent two weeks ago to 1.06 billion pounds (1.82 billion euros, 1.52 billion dollars).

But its task of winning through was made harder last week when London Stock Exchange (LSE) shareholders voted to maintain a cap on stakes held by individual companies at 4.9 per cent.

This threshold can now only be scrapped by 75-per cent support among LSE shareholders, meaning that OM now needs three quarters of all LSE shareholders to back its offer.

By Friday, OM said it had received support for a total of 810.725 LSE shares, or 2.73 per cent of the exchange's issued ordinary share capital.