The chairman of the European Convention says Britain's interests are being taken into account in the drafting of a new EU constitution.
Mr d'Estaing wants to see a stronger EU
Former French President Valery Giscard D'Estaing says he is aware of British concern over several "sensitive" areas and stressed he is "wary" about draining away any of the powers of national parliaments.
He told BBC1's Breakfast with Frost programme: "The idea of offending or
destroying Britain is nonsense."
Conservative Party leader Iain Duncan Smith told BBC Radio 4 changes to Britain's relationship with Europe should be put to a referendum.
'No name change'
But Welsh Secretary Mr Hain, also speaking on Breakfast with Frost, said the constitutional treaty being discussed by Mr d'Estaing did not need to be "subject to a referendum".
Mr d'Estaing is chairman of a convention engaged in a wide-ranging debate on the EU's future organisation and structure. The publication of the first draft of the constitution is expected on Monday.
He said there would be a number of changes to the convention report following discussions with Prime Minister Tony Blair a few days ago.
The word "federal" will probably be dropped, there will be no proposals towards a harmonisation of tax systems and there will be no name change mentioning a "united Europe".
The EU's aim is to adopt the new constitution in time for the admission of 10 new members in May 2004.
An inter-governmental conference will take the final decision - and that decision will have to be unanimous.
I am confident we can get
a good result for Britain in the end
Mr Giscard d'Estaing said: "We should be a stronger Europe, better organised. Not to compete, not to
antagonise but just to have confidence in what we are and where we stand in the
world of today."
He said he was in favour of the very clear definition of "the whole of the European
institutions on one side and national institutions on the other side".
Britain's long-standing problems with Europe came about because "you never made up your mind", Mr Giscard d'Estaing added.
And he called on Britain to consider Europe as a "full option".
"I would say if you want to be, as I wish, a leading country in
Europe, I think you should make up your mind in the next 10 years."
The Conservative leader told BBC Radio 4's World This Weekend: "We think this is a huge change to the way in which British people will be governed.
"Don't trust the politicians on this. Give the British people a real choice.
Give them a fair deal, let them have their say."
Chaired by Valery Giscard d'Estaing
Holding year-long discussions
Aims to simplify treaties
Trying to decide balance of power between Brussels and governments
He added: "What you have got here is a proposal for a new constitution."
Mr Hain said the changes being proposed by the convention would be "best dealt with in Parliament, as all other changes
have been including under Mrs Thatcher when she used the single market to allow
businesses to trade with Europe on an equal footing."
He stressed there was still around 12 months of negotiations left to run where Britain would have a veto.
"Let's just calm down and see how this goes. So far we have made very good
progress," he said.