Recasts, adds more detail from speech, background, bullet points

By Simon Jessop

LONDON, June 24 (Reuters) - United Nations Secretary-General Antonio Guterres said on Wednesday that climate adaptation must be treated as a core priority for governments, warning that urgent action is needed to close a widening financing gap as climate risks intensify.

As droughts, floods and other extreme weather events affect communities worldwide, he told policymakers and finance leaders at London Climate Action Week that adaptation has so far been undervalued and chronically underfunded.

"Finance ministers, central banks, planning ministries and public investment authorities must treat climate risk as core economic policy in order to mobilise greater domestic resources," he said, urging governments to incorporate climate risk across everything from fiscal policy to regulation.

To boost funding, Guterres called for windfall taxes on fossil fuel companies, with proceeds directed toward adaptation efforts and climate-related losses and damage.

He also said shareholders in multilateral development banks must give lenders "far greater firepower," including increased capital, to scale up financing for resilience-building projects.