LONDON, Jan 30 (Reuters) - Access to Britain's fishing waters is not up for renegotiation in any talks with the European Union over possible changes lawmakers have demanded to the country's exit deal, Prime Minister Theresa May said on Wednesday.

May has said she wants to reopen negotiations on Britain's Withdrawal Agreement with the EU, something she had previously warned might see other countries also make new demands including over access to British fishing waters after Brexit.

When asked by a lawmaker in parliament whether she would fight any attempts by EU members to retain guaranteed access to Britain's fishing waters, May said: "I'm very clear ... we had that agreement and it is not up for renegotiation." (Reporting by Kylie MacLellan and William James, editing by Elizabeth Piper)