Thousands of junior doctors in the United Kingdom launched a five-day strike on Friday, following a breakdown in pay negotiations with the Labour government.

Doctors formed picket lines outside hospitals nationwide after last-minute talks late Thursday failed to yield an agreement. The strike is the latest in a series of walkouts over pay and working conditions that have affected the UK’s National Health Service (NHS) in recent years.

The action comes despite a 22.3 percent pay increase package accepted in September — shortly after Prime Minister Keir Starmer’s Labour Party assumed office. However, junior doctors, who are below consultant level, insist the offer does not adequately address what they describe as a 21 percent real-terms pay erosion since 2008.

“We’re not working 21 percent less hard, so why should our pay suffer?” said Melissa Ryan and Ross Nieuwoudt, co-chairs of the British Medical Association’s (BMA) junior doctors’ committee, in a joint statement.

Prime Minister Starmer, writing in The Times on Friday, made a direct appeal to the striking doctors, warning that the walkout could endanger patient care and deepen the crisis in the NHS.

“Launching a strike will mean everyone loses,” Starmer said. “Lives will be blighted by this decision. Our NHS and your patients need you.”

Health Secretary Wes Streeting echoed the plea, stating in a letter published in The Telegraph that the government could not afford further increases in doctors’ pay this year.

The previous Conservative-led government had rejected the BMA’s call for a 35 percent pay restoration to reflect cumulative inflation over the past decade. Upon taking office, Labour resolved several pay disputes with other public sector workers, including teachers and train drivers, the latter of whom secured a controversial 15 percent raise over three years.

Last year’s industrial actions by doctors led to the cancellation of tens of thousands of appointments and caused significant delays in treatment. The current strike is expected to further strain the already overburdened NHS.