Almost four in 10 patients left trapped in Scottish hospitals despite being fit to leave came from north and north-east Scotland.
New figures show that 61 people could not leave hospitals in Grampian and the Highlands for six weeks or more despite being ready to do so.
Across Scotland, just 156 patients were delayed for the same amount of time.
Last night, opposition politicians said the figures were a “real concern” and demanded action from the Scottish Government.
Health Secretary Shona Robison said “good progress” was being made in tackling bed blocking.
Official statistics for May this year show that 31 patients were kept in NHS Grampian facilities for six weeks or more – down from 44 in the same month last year.
In NHS Highland, 30 people were kept in their facilities for the same amount of time – down from 40 in the same month last year.
Alexander Burnett, Scottish Conservative MSP for Aberdeenshire West, said: “While I welcome the improvement made in the past year in the NHS Grampian area, bed blocking clearly remains a serious issue in the north and north-east.
“NHS Grampian and NHS Highland account for nearly half of all patients facing an unacceptable wait of six weeks or more to be discharged from hospital.”
Scottish Liberal Democrats health spokesman, Alex Cole-Hamilton MSP, said the figures were a “real concern”.
He added: “We know that communities outside the central belt face particular challenges but the fact that well over one third of those kept in hospital for six weeks longer than necessary were in these two board areas raises questions over whether care services are getting the support they need.”
His Scottish Labour counterpart, Anas Sarwar, said: “More than a year ago SNP Health Minister Shona Robison promised to eradicate delayed discharge from out NHS by the end of 2015.
“That’s a promise, made to patients and staff, that has been broken.”
Ms Robison hit back and said the figures showed “a significantly better position than last year”, with 3,500 additional bed days freed up compared to April 2015.
She added: “This is in stark comparison to other parts of the UK where the number of people delayed waiting to leave hospital is on the rise.
“However, tackling delayed discharge remains a key priority for this Government and we must continue to work to reduce delays even further – improving the experience for patients and helping our NHS to run more smoothly.”