Rich countries have been accused of "shirking their responsibility" as a global conference on reducing disaster impact ended with pledges to lower the human cost of catastrophes, but with no firm numerical targets.

Coming as aid agencies struggled to reach remote islands in cyclone-devastated Vanuatu, the "Sendai Framework for Disaster Risk Reduction 2015-2030" sets seven global goals for "the substantial reduction" of losses of life, health and wealth.

Thousands of policymakers from more than 190 nations gathered at the once-in-a-decade conference in Sendai, northern Japan, from Saturday, with the idea of issuing a declaration early Wednesday.

But negotiations overran and the conference closed before dawn Thursday, as wealthy countries battled it out with developing nations, particularly over the issue of global warming, leaving NGOs unimpressed.

Vague targets set included reducing global disaster mortality and damage to infrastructure, while increasing the number of early warning systems and improving cooperation.

The agreement "is being heavily criticised by aid agencies, including ActionAid, who say rich countries are shirking their responsibility to respond to the growing impact of climate change," said the Johannesburg-based ActionAid in a statement.

"We are walking away from Sendai with an international agreement full of fluffy targets," it said. There are "no specific numbers which are needed to hold governments to account for their actions over the next 15 years."

It added: "The language in the text is ambiguous on what rich nations must provide. This is an unacceptable compromise by the world's governments that will ultimately affect people living in poverty the most."

The conference had opened on a grim note as Severe Cyclone Pam swept through Vanuatu, destroying villages and leaving thousands homeless.

On Saturday, Vanuatu President Baldwin Lonsdale made an emotional appeal for international assistance, and later told AFP they needed the world's help to rebuild "everything".

Oxfam Japan said it was "greatly disappointed" at the outcome of the conference.

"There are only ambiguous 'targets' in the agreement but no ambitious and clear numerical targets for the next 15 years," it said, adding the agreement also "has no clear promise on financial and technological supports for preventing disaster risks."

"In this conference, for which an enormous amount of money was spent, governments failed to capture a precious opportunity to promise concrete actions for disaster victims now and in the future," it said.