The National Gallery of Australia (NGA) may have to return more precious artefacts to India as evidence mounts they were bought from a smuggling ring.

Key points: The items in question are a scene from the life of Buddha and a statue of the goddess Pratyangira

The items in question are a scene from the life of Buddha and a statue of the goddess Pratyangira The antiquities dealer who sold the two sculptures to the NGA is facing trial in India

The antiquities dealer who sold the two sculptures to the NGA is facing trial in India The gallery says it is possible the sculptures will be returned

The gallery has already returned a $5.6 million statue bought from a smuggling network in 2008.

But reports have emerged that Indian investigators believed two more artefacts were linked to the network.

Illicit antiquities trade expert Jason Felch said there was mounting evidence that an 1,800-year-old limestone carving showing a scene from the life of Buddha, and a 12th-century statue of the Hindu goddess Pratyangira were also stolen.

"Investigators here in the United States have had evidence for some time that those objects were supplied by illegal traders in India," Mr Felch told AM.

Antiquities dealer Subhash Kapoor, who was jailed in India and has been facing trial, sold the two sculptures to the National Gallery in Canberra.

Mr Felch said Kapoor had provided the museum with documents claiming the objects had been out of the country for some time, when in fact the statues had recently been smuggled out of India.

The gallery paid $800,000 for the Buddha and nearly $340,000 for the goddess Pratyangira in 2005.

Indian authorities have been cracking down on Kapoor's suppliers in India and arrested trader Deena Dayalan.

The Australian newspaper has reported authorities believed Dayalan sold Kapoor the two sculptures.

"Dayalan allegedly organised networks of thieves who would break into Indian temples and steal these objects," Mr Felch said.

"He would then arrange for their export to Manhattan, where they were packaged and readied for market by Kapoor and then sold onto museums."

Objects could be returned: National Gallery

In a statement the gallery said it was possible the two other sculptures would also be returned.

"The NGA has conducted thorough provenance research into these two sculptures and is working closely with Indian authorities on the next steps," it said.

"The Crennan Report, which the NGA released in February, identifies these sculptures as having suspect and insufficient provenance and it is certainly possible they will be returned."

Mr Felch said this was a change from the gallery's previous stance.

"I personally did a lot of reporting of these cases and spent a fair bit of time asking the National Gallery of Australia to comment on the investigation that we had done, which found very clear evidence that objection in their collection had been looted," he said.

"They dismissed these and I think the controversy that you saw under the last director, that ended in his departure from the museum somewhat in disgrace, was a result of them putting their heads in the sand if you will.

"There's been important changes at the NGA in recent years and there are good indications coming from the current leadership in their openness and their willingness to proactively investigate these objects and share that information with the public."