Rebel Liberal Democrat MPs plan to challenge a decision to deny them a vote on the government’s NHS reforms at the party’s forthcoming annual conference.

Rebels such as former MP Evan Harris had called for a motion demanding further changes to the controversial legislation be debated in Birmingham next week.

The legislation was passed in the Commons last week after Liberal Democrat pressure forced significant changes - though four of the party’s MPs rebelled.

Deputy prime minister Nick Clegg insists there is “not a case” for any further changes to the blueprint but critics are appealing to Lib Dem peers to force the issue.

Baroness Shirley Williams, who has been among the most vocal critics of the reforms, will take part in an on-stage discussion with ministers at the gathering of activists.

But the only other discussion on the agenda, set by an elected committee of party members, is a “topical” debate without the opportunity to vote on any particular conclusions.

Mr Clegg’s key adviser Norman Lamb said the debate offered a chance for party members to “send clear messages to the party in Parliament”.

Mr Lamb threatened to resign over the NHS reforms earlier this year but said his concerns had been met and that it was time to concentrate on a “bigger threat” to the health service posed by the need to find £20bn in efficiency savings.

He said: “My message is: let’s focus on what really matters in the NHS and that is ensuring that financially it is sustainable. That is the massive challenge.”

Mr Harris said however that he expected a challenge to be lodged this week - complaining that the Lib Dem conference was in danger of becoming a “talking shop”.

“There is a strong feeling that the party should use its time to debate matters to a vote and a resolution,” he said.