Animal rights activists protested outside the Indian embassy in Washington on Thursday, accusing Air India of transporting live animals for use in scientific experiments.

People for the Ethical Treatment of Animals (PETA) says it was told in writing by the government-owned flag carrier in May 2012 that it did not, and would not, accept lab animals as cargo.

"Several months later, we got word that they were," PETA's director of lab investigations Justin Goodman told AFP after four PETA activists wearing prison uniforms and animal masks crawled into wire cage outside the embassy.

Air India now handles 20 shipments of rabbits, guinea pigs and mice on domestic flights every month, he said.

"We're letting the Indian government know that this cruelty and dishonesty doesn't fly with travelers around the world," he added.

PETA says many of the world's biggest airlines prohibit the shipping of live animals to laboratories, including Air India's main domestic competitor Jet Airways.

Spokesmen for Air India in the United States could not be reached for comment.

But in a report in the Indian Express newspaper in October 2012, an Air India executive was quoted as saying that the ban on lab animals had been issued "in order to avoid adverse publicity" and later withdrawn.