Mr Ji Cheng, a partner from the Deheng Law Office in Beijing, said he had recently filed the suit against milk producer Sanlu Group at the Zhenping county court in central Henan province.

'We handed over all the documents to the court, and now we're waiting for a reply,' he said.

The infant, identified in the local media as a one-year-old boy from Zhenping county, started drinking Sanlu powdered milk shortly after his birth in July last year.

He was diagnosed with a kidney stone this summer, allegedly due to melamine mixed into the milk powder, and has since been hospitalised, most recently in Beijing.

The parents of the boy are demanding 150,000 yuan (S$31,500) in compensation from Sanlu Group, according to Mr Ji.

'I believe the figure of 150,000 yuan is reasonable,' he said, citing the medical costs incurred by the parents in the weeks since their child was admitted to hospital for emergency treatment.

The tainted milk scandal has sent shock waves through China's dairy industry, following the discovery that melamine in milk killed four children and has left 53,000 others sick.

The scandal continues to escalate, as a growing number of companies have pulled their China-made products off shelves in overseas markets.

However, Chinese lawyers seeking redress for infant victims claim they are facing growing official pressure to abandon the efforts.

Scenes of thousands of parents crowding hospitals, seeking help for babies ill from toxic milk powder, have stoked widespread public dismay in China.

Reflecting that anger, local rights advocates and lawyers have mobilised to support families seeking redress, possibly by suing dairies or officials who failed to disclose the problem.

However, organisers of the campaign and some of the lawyers said this week that officials in some provinces have pressured volunteers or their bosses to give up the campaign.

'About two dozen of the lawyers have called these past days to say they want to quit the volunteer advice group,' said Mr Li Fangping, a Beijing lawyer who helped organise the group soon after public news of the poisonings emerged.

'Some of them said that they or their offices were told they would face serious repercussions if they stayed involved.'

The pressure has by no means deterred all the lawyers to drop out, and it does not appear to have been uniformly intense, Mr Li and other participants said. The group still has about 120 lawyers ready to give free advice.

But the rash of warnings suggests the government does not want lingering political and legal fallout from the milk scandal.

'I'd guess they see this issue as just too sensitive for lawyers and court cases,' said Mr Zhou Shifeng, a volunteer lawyer from Beijing who said he had heard of the pressure.

AGENCE FRANCE-PRESSE, REUTERS