WASHINGTON

UN's relations with Israel are "complex and challenging," said a spokesman on Monday.

"The lines of communications are open, but the relationship remains complex and challenging," Stephane Dujarric told reporters during his daily briefing.

Stating that the UN continues to speak with Israeli officials to facilitate humanitarian aid operations in Gaza, Dujarric said the international body is trying to make the aid process "more effective" and "quicker."

"We are trying to deliver humanitarian aid in the middle of a conflict. That is always a challenge, that is always dangerous not only for those who are delivering aid, but also for those who are receiving aid. We're also trying to deliver aid in the midst of a conflict in a highly difficult political situation. Nothing about this is easy," he said.

UN Secretary-General Antonio Guterres in early December invoked a rarely used tool in his push for a cease-fire in Gaza, Article 99 of the UN charter, which sparked outrage among Israeli diplomats.

Israel's UN envoy, Gilad Erdan, argued that the genocide case against Israel heard last week by the UN’s International Court of Justice is unfounded and accused the UN of becoming “an accomplice to terrorists."

*Serife Cetin in New York contributed to the story in New York