The Labour leadership suffered its second conference defeat of the day this afternoon when delegates passed a motion condemning government plans to privatise health services.

A rebel motion, condemning the "breakneck speed of change" in the NHS and opposed by the party's ruling national executive, was carried on a show of hands.

It followed a defeat earlier in the day when delegates called for more investment in council housing.

The vote came at the end of the stormiest debate so far of Labour's Manchester conference and as hundreds of health workers held a 24-hour strike in a bitter row over the privatisation of NHS Logistics, a supply arm of the health service.

Moving the successful motion, Unison's general secretary, Dave Prentis, warned of an NHS "in crisis" and attacked "market madness".

The health secretary, Patricia Hewitt, sought in vain to have the Unison motion revoked.

Carol Dean, of Tamworth constituency branch, put forward a separate motion supporting the government, accusing Unison of "going their own way" rather than reaching a consensus before today's debate.

During the debate, a round of speakers took to the platform to denounce privatisation in the NHS.

Fury broke out as Mr Prentis was prevented from completing his speech tabling the motion, in which he attacked the "dangerous change of direction" which saw competition and "divisive markets" penetrating the NHS.

The attempt to stop him from finishing his speech as he ran 30 seconds over his allotted time prompted Jack Dromey, the deputy general secretary of the T & G and treasurer of the Labour party, to come to the stage to describe the move as "discourteous" and "outrageous".

Mr Prentis used his five minutes to warn that a "national tragedy was unfolding" as the NHS saw daily reports of cuts and redundancies, staff dazed by a "permanent revolution" of change and restructuring and instability created as hospitals were forced to compete each other for patients.

Mr Prentis also condemned the decision to close NHS Logistics and outsource the supply provision of NHS equipment to a German "union-busting" company, DHL.

As Mr Prentis spoke, dozens of delegates stood and waved paper fans reading "Save our NHS".

"A Labour government is parcelling off the service, a privatisation of choice driven by dogma which was rejected by the Tories in 1995 as a privatisation too far, with Labour ministers in denial, denigrating an award-winning service as having no place in the NHS," Mr Prentis said.

But Ms Hewitt defended the decision to hive off NHS Logistics' work to the private sector on the grounds that it would present massive savings for NHS services, while conceding there were limits to the role of the private sector within public services.

"I am not going to turn my back on £1bn of savings," the health secretary told the conference.

Ms Hewitt insisted that the employment rights the workforce currently enjoyed would continue under DHL.

"There will be no two-tier workforce and staff will be transferred on comparable terms and conditions," she said, adding: "We are not making change for changes sake".

Earlier today, Ms Hewitt talked to some of the NHS Logistics workers who have taken two days of strike action in protest over the closures.

DHL provoked the ire of the GMB after it wrote to the union's general secretary, Paul Kenny, calling for one of its officers, Mick Rix, to be sacked over his comments about the company.

It emerged today that a DHL parcel depot in Colney, Hertfordshire, will close with a loss of 30 jobs as part of a 3,000-strong staff reduction programme.

Labour's conference will hear tomorrow morning the outcome of a card vote on the NEC's own statement on health, which contradicts the rebel motion, although it echoes the minister's view that there should be circumscribed limits on private sector involvement on the NHS.

The Unison motion was passed on a show of hands, while Ms Dean withdrew her motion backing the government.