UNITED NATIONS - The United Nations and its partners have fed more than 1 million people in the Gaza Strip since the ceasefire took effect one month ago, a senior UN official said on Monday.

"One month after the Gaza ceasefire, we are continuing to seize every opportunity to save lives," said Tom Fletcher, UN Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator, in a statement.

Since the ceasefire between Israel and Hamas in Gaza took effect on Oct 10, nutrition sites have been reopened, hospitals are treating more patients, roads have been cleared, and vital immunizations have been resumed, he said.

In addition, water lines have been repaired, winter clothes and blankets distributed, and mental health and psychosocial services delivered, said Fletcher.

"But many obstacles remain. We're working to overcome red tape, enable essential humanitarian partners, open more crossings and routes, and navigate continued insecurity," he said.

Over the weekend, UN teams reported shelling and navy fire in different parts of Gaza, though at much lower levels than before the ceasefire, Farhan Haq, deputy spokesperson for the UN secretary-general, told a daily briefing on Monday.

In some areas, UN teams still have to coordinate every movement in advance with the Israeli authorities, he said, noting that on Sunday, UN personnel made eight coordination attempts, with only two fully facilitated and four impeded on the ground.

"Despite the challenges, the UN and our partners are seizing every opportunity to expand operations," Haq said.

UN agencies on Sunday kicked off the catch-up campaign for routine immunization, nutrition and growth monitoring, focusing on children who missed earlier vaccination campaigns and aiming to reach 44,000 children overall. Since the ceasefire, UN humanitarian partners have been providing water trucking services through 2,000 locations across the Gaza Strip, according to the spokesperson.