NHS to get £250m as health secretary says no patient should wait more than a year unless there is strong clinical justification

No one should have to wait more than a year for NHS treatment in England unless it is clinically necessary, the health secretary, Jeremy Hunt, has said.

Hunt announced a £250m drive to eliminate "unacceptable" 12-month waits, with more than 100,000 additional treatments to take place in the NHS over the summer.

He acknowledged that the focus on "long waiters", whose conditions are often more complex and time-consuming, would mean the NHS would miss 18-week waiting-time targets over the coming months.

But he insisted that this would constitute a "managed breach" of the target, and it would be met again by the start of 2015.

Hunt highlighted a dramatic cut in the number of people waiting 12 months or more for treatment, which has fallen from 18,458 when the coalition government came into power in 2010, to 574 now.

He blamed the former Labour administration for imposing "perverse" incentives, which he said had led hospitals to prioritise those who had not been waiting long over those who had passed the 18-week limit.

He is expected to tell hospital staff in Guildford, Surrey, on Monday: "No one, except in exceptional circumstances, should have to wait more than a year. We need targets that help patients get treatment when they need it, not targets followed blindly with no regard for the impact on individuals.

"The NHS is confident that, in the end, it will continue to meet the huge challenges ahead if it leaves room, among many loud, competing pressures, for the quietest but most important voice of all: that of the patient."

Hunt has ordered a casework review of every patient waiting close to or more than 52 weeks, to ensure they are treated as a priority and are not made to wait for an operation unless there are strong clinical reasons.

The summer drive to reduce long waits will see 100,000 treatments given to people who have been waiting more than 18 weeks, including 40,000 patients who will be admitted to hospital.

England's ageing population means the NHS is now dealing with 100,000 more referrals for treatment each month than in 2010, while hospitals are performing an extra 2,000 operations a day, according to the Department of Health.

Despite this extra demand, the NHS has kept average waiting times below 10 weeks and fewer people are waiting longer than 18 weeks, a spokesman said.