LONDON — Thousands of people have marched through London demanding more government money for Britain's overburdened National Health Service.

Trade unions and the main opposition Labour Party backed the "NHS in crisis: Fix it now" protest.

Marchers with placards proclaiming "Save our NHS" and "More staff, more beds, more funds" made their way through central London on Saturday toward Conservative Prime Minister Theresa May's Downing St. office.

Britain's state-funded health service has been under mounting pressure, with demand from a growing, aging population rising faster than investment. Winter illnesses and an exodus of stress-hit medical staff have led to thousands of canceled operations and long waits for ambulances and emergency treatment.

The British government says it is putting more money into health care and training more doctors and nurses.