Locum doctors have been accused of running an “organised campaign” to hold the NHS to ransom after dozens demanded pay boosts of up to 50 per cent.

NHS watchdogs said medics employed via agencies are refusing to work at the last minute, leaving dangerous gaps in medical cover, as pressures on hospitals mount.

Jim Mackey, chief executive of NHS Improvement, accused doctors of colluding to try to get pay boosts in ways which could see some struck off.

He spoke out as it emerged that a string of hospitals have been pushed to the brink of crisis, by agency doctors withdrawing from shifts, after their pay demands were resisted.

The crisis stems from new rules - introduced this week - which attempt to clamp down on tax avoidance.

Health regulators say some locum doctors are abandoning shifts when pay demands have been refused - knowing that the NHS is braced for a surge in pressures over the long Easter weekend.

Mr Mackey accused doctors of a “very organised campaign” as it emerged that: