Heads of Crown Dependencies meeting in London ahead of vote
An amendment to UK's Financial Services (Implementation of Legislation) Bill is "unconstitutional and undemocratic".
Treasury Minister Alfred Cannan claims the move - which is being driven by a number of MPs, including Margaret Hodge - is "opportunistic", to push their own agenda forward.
The chief minister is in London today for talks.
Howard Quayle will be joined by the chief ministers of Jersey and Guernsey.
A joint statement from the three jurisdictions accused the UK government of contravening the established constitutional relationship between the British government and the Crown Dependencies.
Mr Cannan was speaking live on Mandate this morning.