The number of people who have long waits for NHS treatment has jumped 61% in one year, according to new figures.
Data for England shows 11,857 people in June had been waiting over six months for treatment, up from 7,360 in June 2010.
Of these, 718 people had been waiting more than a year for their NHS treatment to start, up on the 430 in June 2010.
The total number of people experiencing longer waits has been rising across the NHS since the coalition came into power.
Figures out earlier this month showed the number waiting more than four hours in A&E has almost doubled in the last year, despite a drop in overall attendances.
And the number of people waiting more than six weeks for key NHS tests has almost quadrupled in the last year, although more tests were carried out.
The data shows around one in PCTs in England are not hitting the target for 90% of patients to be seen within 18 weeks.
This is more than double the figure a year ago.
The data shows that 31,483 patients were waiting longer than 18 weeks for treatment, up 9,063 on the figure for May 2010 when the government came into power.
Overall, the NHS is keeping to the target for 90% of NHS patients to be seen within 18 weeks but only because some trusts are outperforming and making up for those who fall short.
The government insists waiting times are stable.
Data calculated by the Department of Health shows that people occupying the mid-point in the range of waiting times had a 8.7 week wait in June this year.
It says comparable data shows waiting times have fluctuated between 7.6 weeks and 9.1 weeks since December 2008.
Health minister Simon Burns said: “Average waiting times are low and remain stable.
“The vast majority of patients still receive treatment within 18 weeks.
“We are committed to driving improvements in performance and the quality of care that the NHS provides - including keeping waiting times low.”
Shadow health secretary John Healey said: “Compared with last year, a third more patients are waiting longer than 18 weeks for hospital treatment and the situation is getting worse by the month.
“With the figures also showing a doubling since May 2010 in the number of patients waiting over a year for treatment, it is clear that people can’t trust David Cameron to keep his NHS promises.
“The NHS is starting to go backwards again under the Tories.
“Instead of concentrating efforts on improving services for patients, ministers have spent a wasted year forcing through their reckless and damaging NHS reorganisation.”