London's health organisations will need to 'work as one NHS' to meet the 'challenge' of dealing with the Greater London Assembly and a directly elected mayor, managers have been told.

Nigel Crisp, newly appointed director of the single NHS region for London that goes live in January, told an Institute of Health Services Management meeting last week that the mayor and GLA 'will want to question our performance'.

'This could be very difficult for us and put us on the defensive,' he said. 'A lot of people are asking how we develop the sort of mature relationship with the new politicians that will be necessary.

'I am sure a large part of this will be about working as one NHS, speaking broadly with one voice and taking the initiative.'

Ministers are due to introduce legislation to create London's mayor and assembly in the parliamentary session that started this week.

Mr Crisp also said the new regional office could be 'overwhelmed by problems' if health authorities, trusts and other organisations were not clear about their own roles.

He also warned that the London region could 'raise expectations beyond what is reasonable' if a long-term strategy was not developed 'with a clear sense of priorities and progress against goals year on year.'

The region 'would be criticised', he added, if it did not set up London- wide protocols for specific healthcare issues such as 'dealing with the most severely injured people' or cancer.

Mr Crisp identified other priorities as 'modernising hospitals', developing 'networks' of primary, secondary and community care and bringing primary care up to 'the same level as the rest of the country'.

Managers warned that the new region would have to tackle shortages of resources and staff.

Alan Walker, a commissioning manager at Merton, Sutton and Wandsworth HA, said London needed 'a fair share' of resources, particularly for primary care.

Mr Crisp said central government had spent£30m on primary care in London in the wake of the Tomlinson report.

The present government had indicated that London would have to 'continue to have that budget' following the Turnberg review of the capital's health services, he added.

Russell Vandyck, best practice manager at Guy's and St Thomas' trust, said the new office should address the problem of hospitals 'poaching' nurses from each other.

Mr Crisp said that it would be up to trust managers to deal with the issue, but that the Executive locally could 'provide financial support' to help trusts to work together in attracting staff to London.