United Nations (PTI): Stressing that even one instance of sexual abuse by UN peacekeepers can't be taken lightly, UN General Secretary Ban Ki Moon termed such incidents as "painful" and said the UN will "continue to address (the issue) candidly, comprehensively and robustly".

Ban's statement comes in the wake of report by a British NGO alleging rampant sexual abuse of children at the hands of peacekeepers and international aid workers in war zones and disaster areas.

Expressing his deep concern over abuse by aid workers and peacekeepers, Ban said "the abuse of children by those sent to help is a significant and painful issue."

As the report cited, the UN has already taken several steps to address the problem, including setting up conduct and discipline units in all missions to boost training for all personnel, he said.

But "we are determined to redouble our efforts in this regard and to work with all of our partners to implement fully our policy of zero tolerance of sexual exploitation and abuse by UN personnel," Ban said in a statement.

The United Nations officials, not denying the allegations made in the report, have pledged to work aggressively to investigate the allegations and cooperate with the host countries to bring the abusers to justice.

However, they admitted their efforts were hampered as the ultimate authority, under the agreement with troop contributors, is the host country and UN can only help to provide evidence.

A senior official pointed out that one difficulty they face is that the age of consensual sex is lower in some countries and hence the accused cannot be prosecuted.

The officials promised to study the report, strengthen the mechanisms and take steps which would encourage people to come forward to report on the incidents.