The number of patients waiting over six months for hospital treatment has nearly doubled since the end of last year, new figures show.

Between the end of December and the end of April last the total number of patients waiting over six months for hospital treatment jumped from 6,038 to 11,348, a rise of 88%.

The figures from the Department of Health show that waiting lists are on an upward spiral again after Minister James Reilly's initiative to cut lists made some progress last year.

The number of patients waiting between nine and 12 months for treatment has increased from only 71 at the end of 2012 to 3,062 at the end of April, while the number waiting over 12 months for treatment has risen from 36 to 653 in the same period.

The figures also show that the numbers waiting between six and nine months has risen from 5,931 to 7,633.

The total number of patients awaiting treatment in all time categories has increased from 44,047 to 47,943 in four months.

The average waiting time for treatment now stands at three months, compared to 2.5 months at the end of 2012.

Including the numbers waiting for colonoscopies and gastroscopies, the total on waiting lists now stands at 56,645, compared to 51,708 at the end of December.

The Department of Health and HSE have set a target of having no-one waiting more than eight months for hospital treatment by the end of this year.