A Massachusetts Supreme Court justice yesterday overturned a ban on recent connections to the strained Boston-area sewer system, but a federal environmental official immediately said he would ask a federal judge to reimpose a ban.

Supreme Court Justice Joseph Nolan's decision was made without comment after a hearing on Superior Court Judge Paul Garrity's week-old ban against new sewer connections in the Boston area.

Shortly afterward, Michael Deland, a regional Environmental Protection Agency director, said, "The time has come for the federal government to act," and promised to file suit in federal court next month to reinstate Garrity's ruling. Deland said Boston is the last big city in the nation without treatment of the sludge that empties into its harbor.

The legislature has taken no action.

Garrity's moratorium was issued in an 18-month-old suit filed by the city of Quincy, which sued the Metropolitan District Commission and state officials over the harbor pollution, largely due to the dumping of sewage.

State Assistant Attorney General Michael Sloman had argued that the ban would create an "economic meltdown" by halting millions of dollars in construction in the 43 cities and towns that buy sewage service from the Metropolitan District Commission.