Laws to protect the Sumatran tiger are failing to prevent body parts of the critically endangered animal from being sold openly in Indonesia, according to a report released today.

Body parts including canine teeth, claws, skin pieces, whiskers and bones were found on sale in one in 10 of the 326 retail outlets in 28 cities and towns across Sumatra that were surveyed during 2006 by the wildlife trade monitoring body, Traffic.

Its report, The Tiger Trade Revisited in Sumatra, found tiger parts being sold in goldsmiths, souvenir and traditional Chinese medicine shops, and shops selling antique and precious stones. Trade was concentrated in Medan, the capital of North Sumatra province, and Pancur Batu, a smaller town nearby, the report found.

Based on the number of teeth on sale, the survey estimates that 23 tigers were killed to supply the products found.

Traffic says this figure is down from its last survey in 1999-2000, which estimated that there were 52 tigers killed per year for the trade in body parts.

"Sadly, the decline in availability appears to be due to the dwindling number of tigers left in the wild," said Julia Ng, programme officer with Traffic south-east Asia and lead author of the report. "The Sumatran tiger population is estimated to be fewer than 400 to 500 individuals. It doesn't take a mathematician to work out that the Sumatran tiger will disappear like the Javan and Bali tigers if the poaching and trade continues."

The Sumatran tiger is listed as critically endangered on the IUCN-World Conservation Union's "red list" of threatened species – the highest level of threat that a species may become extinct in the wild.

Indonesia's only wild tigers are found on the island of Sumatra. Wild Bali and Javan tigers became extinct last century due to habitat destruction and hunting.

Despite international and domestic bans preventing trade of the animal, a thriving black market for tiger skins and bones is threatening to wipe out the world's remaining wild tiger population.

Traffic says that despite providing Indonesian authorities with the details of traders involved, it is not clear whether any serious enforcement action has been taken.

"Successive surveys continue to show that Sumatran tigers are being sold, body part by body part, into extinction," said Heather Sohl, wildlife trade officer at WWF, which runs Traffic as a joint programme with the IUCN. "This is an enforcement crisis. If Indonesian authorities need enforcement help from the international community they should ask for it. If not, they should demonstrate they are taking enforcement seriously."

The report recommends that resources and efforts should concentrate on effective enforcement to combat the trade by arresting dealers and suppliers. It says trade hotspots should be continually monitored and all intelligence should be passed on to the authorities for action. Those found guilty of trading in tigers and other protected wildlife "should be prosecuted to the full extent of the law", it says.

"We have to deal with the trade. Currently we are facing many other crucial problems which, unfortunately, are causing the decline of Sumatran tiger populations," said Tonny Soehartono, the director for biodiversity conservation for Indoneia's ministry of forestry. "We have been struggling with the issues of land use changes, habitat fragmentation, human-tiger conflicts and poverty in Sumatra. Land use changes and habitat fragmentation are driving the tiger closer to humans and thus creating human-tiger conflicts."

Sumatra's few remaining tigers are under threat not only from the illegal wildlife trade in their body parts, but from loss of their habitat due to deforestation. Unless tackled immediately, these combined threats will be the "death knell" for Indonesian tigers, Traffic says.

"The Sumatran tiger is already listed as critically endangered," said Jane Smart, the head of the IUCN's species programme. "We cannot afford to lose any more of these magnificent creatures."

At last year's climate change summit in Bali, the Indonesian president launched a conservation action plan to protect the Sumatran tiger. As it chairs this year's Asean Widlife Enforcement Network, Traffic is urging Indonesia to show leadership in south-east Asia by taking action against the illegal wildlife trade.