Thousands of nurses in Northern Ireland warned "enough is enough" as they began to strike for the first time today.

Crowds of demonstrating healthcare workers protested outside hospitals across Northern Ireland in an unprecedented show of anger at pay levels they say are lagging behind counterparts in England and Wales and under-staffing.

The action saw around 9,000 members of the Royal College of Nursing (RCN) union walk out this morning for 12 hours, supported by other healthcare workers including paramedics. They returned to work tonight.

Routine medical appointments have been cancelled, minor injury units closed and there will be delays to some ambulance responses. Social services workers are also taking industrial action.

RCN Northern Ireland director Pat Cullen said: "They have tolerated this for so long and they say today enough is enough and we need to see something change for patients."

The political vacuum caused by the collapse of powersharing at Stormont means no ministers are in place to decide whether to grant the pay demands or use extra cash to reduce Northern Ireland's long waiting lists for treatment.

A short distance from Stormont, at the Ulster Hospital in East Belfast, more than 100 striking nurses and healthcare workers gathered either side of the main gates for a noisy protest.

A speaker played music and car horns from passing motorists sounded constantly in support. A few ambulances turned on sirens in a show of solidarity.

Nurses cheer as an ambulance beeps its horn in support outside the Royal Hospital in Belfast

A total of 1,600 outpatient appointments have been cancelled in the Ulster Hospital's administrative area. Only nine of 160 planned surgeries are going ahead.

Nurses in Northern Ireland are paid up to £4,677 less than counterparts in England and Wales.

Around half are considering leaving the profession because of pressure caused by under-staffing, the RCN said.

Civil servants running public services cannot find enough extra cash to satisfy the RCN; while just under 2,800 posts are unfilled.

Spending on temporary agency staff to fill gaps has doubled.

A newly-qualified registered nurse in Northern Ireland earns £1,875 less than in Scotland and £1,419 less than in England and Wales.

For a specialist nurse, the difference is up to £4,677, the RCN said.

Northern Ireland Secretary Julian Smith has said finding a solution will be among his top priorities during talks he has called with the political parties.

Sinn Féin and the DUP suffered some reverses in last week's UK General Election.

They face another Assembly election if they do not agree by next month to return to power-sharing and retake control of increasingly-stretched public services.

Nearly 300,000 people in Northern Ireland were on a waiting list for a first appointment with a consultant, according to Department of Health figures published last summer.

Industrial action is also planned by the Unison, Unite and Nipsa trade unions, which cover ambulance paramedics and jobs such as cleaning, portering, catering and administration. Services such as cancer care will be exempted.

All emergency departments will remain open as normal.

All patients and service users affected by cancellations of appointments and service closures have been notified by their local health trust, which runs services, and appointments will be rescheduled.

The Northern Ireland Ambulance Service will be prioritising 999 calls and those calls that are less serious in nature, potentially, face a delay in response times.