Chimpanzees who have spent their lives in US research labs being tested should now be retired in a leafy sanctuary, scientists have recommended.

More than 300 chimpanzees should be retired from government-funded research and sent to live in a sprawling refuge outfitted with play areas under the recommendation.

The proposal from a National Institutes of Health committee is the latest step in a gradual shift away from using chimps as test subjects, because of technological advances and because of ethical concerns about their close relation to humans.

It would affect all but 50 of more than 350 chimpanzees in labs around the country.

The remaining group kept for future federally funded research would have to be housed in spacious conditions laid down in the detail by the committee.

The NIH Council of Councils Working Group proposal, which will go to the agency's director after a 60-day period for public comment, also calls for major cuts in grants to study chimps in laboratories and no return to breeding them for research.

The chimpanzees would be sent to a national sanctuary, Chimp Haven, that opened in 2005 to house former federal research chimps on a 200-acre site in rural northwest Louisiana.

Under an agreement made late last year, before the proposal, nine chimpanzees arrived Tuesday at Chimp Haven from the University of Louisiana at Lafayette's New Iberia Research Center, which no longer has an NIH chimp research contract.

Seven more are expected Thursday and another 95 will arrive over the coming months, sanctuary officials said.

After decades of being taken from cages to be poked and prodded, they will be part of larger social groups with changing access to forest habitats, play yards, courtyards and jungle gyms.

They will get a daily assortment of fresh fruits and vegetables along with their nutritionally balanced biscuits.

The animals that arrived yesterday - eight females and a male between ages 29 and 52 - made up one group housed together at New Iberia, and those scheduled today made up another such social group, said Chimp Haven spokeswoman Ashley Gordon.

They include a two-year-old female and three-year-old male born in New Iberia and coming with their mothers.

Research chimpanzees should be kept in groups of at least seven, with about 1,000 square feet of outdoor space per chimp, according to the proposal.

The space must include year-round outdoor access with a variety of natural surfaces such as grass, dirt and mulch, and enough climbing space to let all members of large troupes travel, feed and rest well above the ground, and with material to let them build new nests each day, the report said.

A $30m cap on total spending for construction and care of Chimp Haven's retirees has been looming. That would stop NIH from contributing 75 percent of the $13,000 annual cost to care for each federal chimpanzee.