The commonwealth of Puerto Rico filed suit yesterday to stop the Carter administration from opening a refugee camp for 4,500 Cubans and Haitians at Fort Allen on this island's south coast.

Two similar suits by a group of labor unions and resident in the Fort Allen area were filled earlier this week.

Puerto Rico's suit charged that the Fort Allen decision was made to take political pressure off President Carter in Arkansas, Florida, Wisconsin and Pennsylvania, where many of the refugees now are housed.

The commonwealth cited eight specific environmental reasons for asking the court to enjoin federal officials from opening the camp.

Many politicians and citizens have been outraged by the announcement that the 940-acre Army and Navy base would be converted into a reception center. They fear that the refugees will be released here, where poverty and unemployment are widespread.

This, however, is not the case, according to federal officials, who insist that the refugees will remain in Peurto Rico only until they can be relocated elsewhere.

In the suit, the commonwealth says that Fort Allen has a sewage treatment plant capable of handling a maximum of 1,500 persons and a water purification plant capable of supplying no more than 4,000, that area electrical facilities are already overloaded and that the wiring of the fort itself is obsolete. Moreover, "It is a low-lying area infested with swarms of mosquitoes," the suit says.

"Hundreds of support personnel will also be housed at the base," the suit says. "Defendants' plan to crowd thousands of refugees into tents within a barbed wire compound, thereby taxing medical, sanitary and waste disposal resources beyond the breaking point and posing a health and security threat both to the refugees and to the surrounding population, constitutes major federal action significantly affecting the quality of the human environment."

The suit also calls for a government environmental impact statement before opening the camp, and says surplus waste water would have to be disposed of in untreated or partially treated form in violation of federal standards.

Today a pollution-control agency, the Environmental Quality Board, issued a cease-and-desist order against Navy Seabees erecting refugee tents on a Fort Allen runway, saying they had not obtained proper permits.