London (AFP) - Iconic works of art by British artist Damien Hirst involving dead animals preserved in giant tanks leaked potentially-dangerous formaldehyde gas during a show at London's Tate Modern gallery, it emerged on Wednesday.

Scientists testing a new sensor for the remote detection of the carcinogenic gas in the 2012 exhibition found levels above those legally permitted, according to a study in the journal Analytical Methods.

"It has been found that the tanks are surrounded by formaldehyde fumes, constantly exuded in the atmosphere (likely via the sealant), reaching levels of 5 ppm (parts per million), one order of magnitude higher than the 0.5 ppm limit set up by legislation," the abstract states.

One work that emitted high levels was Away from the Flock, a 1994 exhibit showing a lamb preserved in formaldehyde solution in a glass and steel box.

Gas was also detected around Mother and Child (Divided), a 1993 work which comprises four boxes containing a calf and cow each bisected, although the exact level was not recorded in the journal article.

Similar tests also revealed formaldehyde gas around some artworks in the Summer Palace in Beijing, although no levels were given. The scientists suggested this could be blamed on new lacquer painted on the old works.

A spokesman for the Tate Modern said: "Tate always puts the safety of its staff and visitors first, and we take all necessary precautions when installing and displaying our exhibitions.

"These works contained a very dilute formaldehyde solution that was contained within sealed tanks." Hirst's representatives had no immediate response to the study which was led by Pier Giorgio Righetti at the Politecnico di Milano in Italy.