French pharmaceutical company Sanofi and Britain's AstraZeneca said  they have agreed to share freely 210,000 proprietary chemical compounds as they pursue the development of new drugs.

Sanofi hailed the move as "a new open innovation model between two major pharmaceutical groups" who normally are major competitors in a multibillion business creating the building blocks of treatments for diseases.

The novel arrangement of exchanging compounds from their separate compound libraries will "allow both to sift a much larger and more diversified number of small molecules likely to become future medicines," Sanofi added in a statement.

The contents of the libraries are usually kept closely under wraps.

AstraZeneca also hailed the multi-year accord, which will reduce the need to spend tens of millions of dollars in developing the compounds separately.

"It enhances the chemical diversity of the compound collections of both companies and allows each to screen a broader, more diverse chemical space as the starting point in the search for new small-molecule medicines," the firm said.

Those which look promising will be classified as "lead compounds" to be taken forward for development.

Mene Pangalos, AstraZeneca's head of innovative medicines and early development, said the deal would "accelerate our ability to identify unique starting points that could become new medicines for patients."