Shares in ArmorGroup, the private security group, rose by more than a quarter on Wednesday after it said it was in talks with a number of parties over possible offers for the company.

Armor has been seen as vulnerable to a takeover since its shares plunged in November after a profits warning that led to the departure of David Seaton, its chief executive. At the time, the group said big contracts in Iraq had been severely affected by an incident in September involving Blackwater, the US private security company, in which a number of civilians died in Baghdad. It warned that operating profits for the year to December 31 would be lower than the $10.6m (£5.4m) reported for the previous year.