Hong Kong has ordered pharmaceutical giant GlaxoSmithKline to recall an antibiotic used to treat infections in children which contained chemical additives, and warned it may sue the drugmaker.

The health department said tests revealed the British firm’s Augmentin antibiotic tablet contained several plasticisers, including diisodecyl phthalate (DIDP), raising “quality concerns”.

But the department said the amount of the chemicals – used to make plastics pliable – uncovered in the Augmentin tablets was “considered unlikely to cause acute harmful effects if taken according to the recommended dosage”.

The health department said in a statement it would “seek Department of Justice’s advice on possible legal actions against (GlaxoSmithKline)”.

“Since GSK could not provide satisfactory explanation on sources of the plasticisers, the quality of the product is in question.”

In a statement, the drug firm said it had launched an “urgent and thorough investigation” to determine the source of the additives.

“GSK does not intentionally use any plasticisers in the manufacture of Augmentin,” it said, adding they were “significantly lower than the levels that the US and European authorities deem as presenting risk to humans”.

Last month, Hong Kong’s health watchdog ordered a recall of the antibiotic in syrup form after it discovered elevated levels of DIDP, warning that long-term consumption at high levels may have adverse effects on the liver.