An Indonesian firm has appealed a landmark court ruling that struck down a contract it had to provide water services in Jakarta, in a case likely to be closely watched as a yardstick of the country's investor friendliness.

Two companies, Indonesia's PT Aetra Air Jakarta and PT PAM Lyonnaise Jaya (Palyja), part of France's Suez Environnement, secured contracts with a company owned by the Jakarta government in the late 1990s.

But the Central Jakarta district court last month ruled in favor of a citizen's group which claimed the companies failed to provide sufficient clean water and annulled the contracts.

"We feel that we have positively helped the stakeholders of this agreement and what was decided at the court was not in accordance with what we had already done," Pratama S. Adi, Aetra's corporate secretary, said of the appeal.

Palyja also said last week it plans to appeal the ruling.

The case represents the first time an Indonesian court has, at the instigation of a number of citizens, decided to invalidate an agreement between a government firm and a private party, Indonesian law firm Hadiputranto, Hadinoto & Partners said in a letter to clients.

"While there is still hope that the higher level courts will rectify the situation, the Central Jakarta District Court's decision is a blow to the government's effort to assure private investors that Indonesia has a solid investment climate underpinning its infrastructure sectors," the letter said.

Fitch Ratings said on Thursday it does not see any immediate refinancing risks for Aetra, but noted uncertainties surrounding the treatment of Aetra's assets and liabilities if the court decision is upheld.