New York  - UN Secretary General Ban Ki-moon on Tuesday expressed "deep concern" over the increased hostilities in northern Sri Lanka, warning that this would have grave humanitarian consequences for civilians.

The Sri Lankan government had requested the relocation of UN humanitarian staff in areas affected by the fighting between government and rebel forces.

Ban said all parties have the responsibility "to take active steps to ensure the safety and freedom of movement of civilians, allowing humanitarian organizations to do their work in safety, as well as to reach persons affected by the fighting who need humanitarian assistance."

He called on all parties to respect international humanitarian law, especially with regard to the principle of proportionality and the selection of targets. He also said there must be a negotiated settlement to the political problems facing Sri Lanka. (dpa)