More than 22,000 owners have declared around 150 tonnes of ivory items, in a campaign to clean up the dirty business and save elephants in the process.

More than 22,000 ivory collectors, including well-known politicians and businesspeople, have reported about 150 tonnes of their ivory items to authorities as the legal deadline to declare the ivory assets ends Tuesday.

National Parks, Wildlife and Plant Conservation Department director-general Nipon Chotiban revealed the figures Sunday.

He said the new elephant ivory law requires ivory collectors to declare their possessions to authorities by April 21 to avoid a hefty fine of up to 3 million baht.

Since the law came into force on Jan 22, the public has been cooperating to disclose assets to the department, Mr Nipon said, adding that between 500-700 people have come to report their possessions daily.

The collectors are members of private companies, associations, foundations, temples and other organisations.

Many of the items reported are pairs of ancient elephant tusks handed down for generations and some of the tusks are believed to be more than 100 years old, Mr Nipon said.

He also said some of the tusks were so huge that collectors had to hire moving companies to move the items while reporting to authorities.

It is the first time that ivory items have been checked nationwide as part of legal measures to curb the illegal ivory trade, Mr Nipon said.

Some notable figures reporting their ivory items to the department include Privy Councillor Palakorn Suwannarat, former prime minister Banharn Silpa-archa and Agriculture and Cooperatives Minister Pitipong Phuengboon Na Ayudhaya.

Chairman and chief executive of Charoen Pokphand Group Dhanin Chearavanont also reported his ivory assets, as well as Bhumjaithai Party leader Anutin Charnvirakul, who owns 16 pairs of elephant tusks.

Mr Nipon said the department will report its progress in implementing the disclosure measures to the secretariat of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (Cites) to show the country is attempting to address the problem.

Thailand is a hotspot for the transnational illegal ivory trade, particularly from Africa.

The measures aim to prevent Thailand from being banned from trading certain agricultural products by Cites — an international treaty to stop trade in wild plant and animal species threatened with endangerment or extinction.

The ivory law also requires ivory traders to register with the department to obtain licences for selling ivory obtained from domesticated elephants, or they may face fines of up to six million baht and three years in prison.

Under the law, traders are banned from selling ivory from wild and African elephants, but not from domesticated elephants.

Prime Minister Gen Prayut Chan-o-cha has previously said the illegal ivory trade has been going on for decades in Thailand and many governments unsuccessfully attempted to tackle the problem.

His government will exercise its power during this transitional period to push for ivory trade-related laws. More regulations are expected to be enforced to deal with the problem, he said.