Shire is stepping up pressure on Baxalta to open its books before the Dublin drugmaker will consider making a higher offer as it tries to break the deadlock over its $30 billion takeover proposal.

Shire chief executive Flemming Ørnskov has spent much of the past two weeks pressing his company’s case and believes that Baxalta shareholders would be open to a deal, sources say.

Shire has not ruled out increasing its offer – which was worth $45.23 a share when the all-paper proposal was made public this month – but it wants access to the US drug group’s accounts first.

Baxalta, for its part, has continued to argue that Shire’s “lowball” opening shot is not a realistic basis for negotiation. – Copyright The Financial Times Limited 2015