The Animal Concerns Research and Education Society (Acres) sent six rescued reptiles back to Malaysia yesterday, the first time that it has done a mass repatriation.

It is part of Acres' efforts to rescue, rehabilitate and repatriate wild animals nabbed by illegal traders for their meat or to be sold as pets.

Yesterday's batch consisted of four giant Asian turtles, categorised as a vulnerable species, and two elongated tortoises, deemed an endangered species.

The first reptile to be successfully released back to the wild was Rahayu, a Malaysian giant turtle, in February last year.

Acres deputy chief executive Kalai Vanan lamented that reptiles are preyed on by illegal traders on a large scale.

"For now, we are focusing on the repatriation of reptiles," he told The Straits Times.

Most of the six reptiles were found wandering in open spaces such as roads before they were rescued.

One of them, a giant Asian turtle named Boltz, was rescued in October 2011 after it had been run over by a truck. It suffered severe internal injuries as well as a large, lightning-shaped crack on its shell that inspired its name.

When Acres was set up in 2001, it focused on advocacy and educational work, raising public awareness on important animal protection issues that were previously unaddressed in Singapore. Its rehabilitation and repatriation efforts were a more recent development.

The construction of an animal shelter in Tengah was stalled in 2008 when the building contractor filled the site with contaminated earth and wood chips that rotted over time. Acres won its suit against A.N.A Contractor in 2015.

Despite the difficulties, Acres opened the Wildlife Rescue Centre in 2009 to begin the vital rehabilitation of rescued animals. In 2013, an outdoor sanctuary was built near the Acres office to house animals rescued from the illicit trades.

According to Mr Kalai, after Boltz was rescued seven years ago, it would look out of its cage longingly whenever it rained. This spurred Mr Kalai to build the outdoor sanctuary, which currently has about 160 wild animals.

Law Minister K. Shanmugam, who was present at yesterday's repatriation, said: "Small as we are, Singapore can make a difference (in wildlife conservation ) worldwide. At least within Singapore, we try and do the right things."

To this end, there have been improvements in terms of legislation and the public sector approach towards animal welfare.

Acres chief executive Louis Ng noted that his society had succeeded in getting the authorities to mete out stiffer penalties to illegal wildlife traders.

Those found guilty now face a maximum fine of $50,000 and/or two years' jail, on a per animal basis. Previously, they faced a maximum fine of $5,000 and/or a year's jail on a per species basis only.