MOSCOW, Russia -- The president of the International Committee of the Red Cross on Thursday said he and Russian Foreign Minister Sergei Lavrov had discussed the need to protect civilians during Moscow's operations in Ukraine.

"We certainly also discussed the international humanitarian law and provisions of the Geneva Conventions in regard to conduct of hostilities... that civilians must be protected," Peter Maurer said at a joint press conference with Lavrov.

Maurer was visiting Moscow after spending five days in Ukraine last week.

He said he and Lavrov had a "very substantive discussion", and that he would also raise the Geneva Conventions that must be respected during a conflict at a meeting with the Russian defence ministry.

These conventions concern prisoners of war and "civilians detained in Russia as well as in Ukraine", he said, as well as "the issue of dead bodies -- civilians and militaries -- that need to be repatriated and brought back to the families".

The Russian minister said "we hope the efforts of the ICRC will bear fruit", calling it an "impartial and independent intermediary".

"Unfortunately we don't have any particular basis to rely on conscientious fulfilment by the Kyiv authorities," he added.

Maurer said the ICRC was committed to enlarging its humanitarian assistance to all citizens affected by the conflict, both in territory controlled by the Ukrainian government and in areas under Russian-backed separatist control.

"We have a particularly challenging frontline at the present moment in Ukraine in the sense that populations are exposed to military operations in urban areas, they are trapped in between frontlines," Maurer said.

Talks between Ukraine and Russia "have produced already certain positive developments in terms of agreements for civilian populations, but we also know that this is insufficient", he said.

Questioned on the humanitarian situation in the besieged southeastern port of Mariupol, he said that the city "has high visibility and attention from the international community".

"But I also wanted to highlight that it is not the only place of concern," Maurer said.

"It's not possible to think about access or evacuation in Mariupol or any other place if we don't have solid agreement and detailed agreement between the militaries on the ground," he said.

Maurer told AFP ahead of his trip to Russia that he hoped to make progress on issues regarding "prisoners of war, the deceased, the conduct of hostilities".