Britain may need treaty change promise in talks with EU - minister

Britain's Prime Minister David Cameron walks back to his hotel after appearing on television on the third day of the Conservative Party Conference in Manchester northern Britain, October 6 , 2015. REUTERS/Phil Noble

MANCHESTER, England (Reuters) - Prime Minister David Cameron may need a promise of changes to European Union treaties to secure concessions he is seeking to keep Britain in the bloc but exploratory talks are going well, Europe Minister David Lidington said.

Cameron is seeking to renegotiate Britain's relationship with the bloc it joined in 1973 as the 'in' and 'out' campaigns prepare for a referendum on membership before the end of 2017.