United Nations, April 15 : UN Undersecretary-General for Humanitarian Affairs, Martin Griffiths has warned that a lack of humanitarian funding in Yemen may undermine the current political momentum. The renewable two-month truce that the warring parties have agreed on is already having a positive impact on the humanitarian situation, he told the Security Council in a briefing on Thursday. However, the humanitarian operation in Yemen remains underfunded, he said. The UN in March raised $1.3 billion in pledges out of the nearly $4.3 billion needed, he added. The UN official said despite newly announced pledges, including $300 million from Saudi Arabia, there is a funding gap, Xinhua news agency reported. "Funding remains the biggest challenge of the response. There's a serious risk that core programs across sectors, including food aid, water, health care, the support for the displaced, will keep scaling down ... and eventually stop if funds don't arrive," Griffiths said. "Allowing the aid operation to collapse would run directly counter to the very positive momentum that I think we're right to honour and celebrate today. And so we're going to do all we can to work with donors from our side to help ensure that these life-saving programs survive," he added. /IANS