Norwich Union (NU) has announced it is sending out details of the new terrorism exclusions for commercial and personal lines products to its intermediaries.
The company also said that wordings for the war exclusions are being standardised for most products.
Director of underwriting John Seaton said: "The insurance industry has been reviewing its approach to terrorism cover since 11 September.
"We trust that the information we are providing to intermediaries will give clarity on the Norwich Union strategy."
These changes will come into effect on 1 July for new business and renewals.