European chemical companies have warned the watchdog that oversees them that it could face legal action if it publishes the names of manufacturers of the most toxic substances in a growing environmental dispute.

The warning was contained in a letter from chemical industry group Cefic to the European Chemicals Agency (ECHA) in Helsinki, released after Reuters invoked freedom-of-information laws.

"Going beyond its remits exposes unnecessarily the ECHA Management Board and its individual members to tremendous and unprecedented liability risks," said the letter, seen by Reuters on Wednesday.

ECHA is charged with evaluating and restricting over 30,000 substances that currently face little regulatory oversight, many of them a potential risk to human health.

Companies that want to sell chemicals must register them with ECHA, including details on toxicity, which the agency will publish on its website.

Activist lawyers ClientEarth and chemicals campaigners ChemSec this week said they had sued ECHA for refusing to disclose the names of facilities producing 356 potentially dangerous chemicals.

"The public knows too little about them, because chemicals companies use the shield of commercial interests," said ClientEarth lawyer Vito Buonsante.

Chemicals companies argue publishing the names will endanger their commercial confidentiality and was not intended when the control laws were agreed in 2007.

Statement Of Fact
Cefic denies it is threatening the agency or using unreasonable pressure and says it is merely stating a fact.

"It is calling an authority on its responsibilities," Cefic's legal chief Jean Claude Lahaut told Reuters. "If a company suffered damage...we could indeed have people complaining to the court of justice."

Cefic says the publishing of company names might help overseas rivals compile a detailed picture of the European chemicals market, and reveal changes of company strategy or innovation of new products.

ECHA told Reuters it had decided to publish company names only in the case of firms that are suppliers of hazardous substances, but that they could request confidentiality.

"We had two years of discussions," said ECHA's Christel Musset. "The industry was totally part of our discussions. We also took legal advice from the European Commission."

Anti-toxics campaigners say company details help them hold companies to account for the quality of the toxics data they submit - a serious issue for the health of factory workers.

Cefic says there are better legal tools for the job. "There are permitting systems... you have occupational health legislation," said Lahaut.

ClientEarth's Buonsante said more transparency would encourage companies to replace toxics with safer alternatives.

"Companies would not have this incentive if nobody knew who is responsible for marketing them," he said.

Cefic counters that naming facilities carries other risks.

"We should underline the increase of risks for potential activist and terrorist actions," it said in an explanatory document sent with the letter to ECHA.