There are still too many complaints of sexual abuse against United Nations troops, the head of peacekeeping operations has said.
The image of UN peacekeeping has suffered in recent months
Jean-Marie Guehenno said the UN had investigated 295 cases under a new reporting system introduced last year.
It could take several more years to reform the system fully, says Jordan's UN envoy who last year urged changes.
The 18 peace missions worldwide employ 85,000 staff from over 100 countries, with a budget of nearly $5bn.
Mr Guehenno said although significant progress had been made in reducing the number of cases of sexual exploitation following an investigation in the Democratic Republic of Congo two years ago, much more needed to be done.
"Allegations being lodged against UN peacekeeping personnel remain high and unacceptably so," he said.
He noted "how hard it is to change a culture of dismissiveness, long developed within ourselves, in our countries and in the mission areas."
Mr Guehenno said only the strict enforcement of a complete ban on prostitution in areas occupied by peacekeepers could strengthen the UN's policy of zero tolerance against sexual exploitation.
Jordanian UN ambassador Prince Zeid Ra'ad Zeid al-Hussein said the increase in allegations was "not entirely unexpected" since there was now a system in place to facilitate complaints.
Briefing the UN Security Council on how the problem was being addressed, the ambassador said it could take three to four years for the reform programme fully to take hold.