Duncan Smith is guilty of betraying Tories, says Patten

The Tory truce that has been in place since the leadership election has ended with outspoken attacks on the party leader, Iain Duncan Smith, by three senior Conservatives.

Chris Patten, the EU commissioner for external relations and a former party chairman, criticised Mr Duncan Smith for "working with Labour" to defeat the last Conservative government over the Maastricht Treaty and attacked him as "extraordinarily rich" for making "emotive lectures on the subject of party loyalty".

Francis Maude, a former shadow foreign secretary, joined the fray, repeating warnings that the party would slip behind the Liberal Democrats "if we fail to turn ourselves into a party with broad appeal".

Stephen Norris, a former party vice-chairman, also issued a stark warning, saying: "If the party swings to the right more violently, if we start to be even more elderly, angry and intolerant ... then it won't just be me, it'll be many, many other people who will simply find something better to do with their lives."

The remarks, made in a BBC television documentary to be screened tomorrow, represent the first serious breach of the party's internal truce since Mr Duncan Smith was elected leader two months ago. The programme charts the rise and fall of William Hague and the rise of Mr Duncan Smith.

Mr Patten told the programme: "Mr Duncan Smith was one of the leading opponents of Maastricht. It's important to remember that the opponents of Maastricht used to plot and work with the Labour Party – ask any of the whips of the time – in order to secure the downfall of the Conservative government and the downfall of its legislation."

The programme charts the slow disintegration of the party leadership in the run-up to the general election and the tensions between rival camps during the Tory leadership battle.

Ann Widdecombe, a former shadow home secretary, attacked Michael Portillo's supporters for briefing against the leadership. She said: "There was a huge amount of destabilising of William and that I resented tremendously."