The World Health Organization launched Sunday a new financing mechanism that aims to raise $7 billion of funds that can be deployed more quickly and flexibly.

The UN agency has traditionally relied on commitments from its 194 member states, but often these are apportioned to specific projects with several conditions attached, including deadlines that can prove too short.

WHO chief Tedros Adhanom Ghebreyesus said commitment increases would contribute $4 billion to the agency's budget of $11.1 billion over the four years through 2028.

"The Investment Round aims to mobilise the other $7 billion," Tedros told attendees at the launch event in Geneva, according to a statement.

The agency will solicit both public and private donors including foundations.

"Instead of waiting for it to come in over the course of four years -- not knowing when it will come, or (how) much will come at any one time -- the Investment Round aims to secure that funding up front," he said.

"This will allow us to make longer-term plans and hire the people we need to implement those plans on more secure contracts."

A meeting will be held in November to secure the funds, with the WHO and countries already sponsoring the new initiative lobbying intensely before then to reach the $7 billion goal.