The Alexandria City Council last night reluctantly but unanimously approved plans for a controversial four-building office complex to be built along the George Washington Memorial Parkway at the north end of the city. But the project still could be halted by the Virginia Supreme Court.

The action, ordered by an Alexandria Circuit Court judge, is the latest in a six-month dispute between the city, the developer and nearby residents over traffic problems the complex is expected to cause.

The city's planning commission approved the office project last April, but that decision was appealed to the council by city residents who said the project would bring Parkway rush hour traffic to a standstill. While the council considered the matter over the summer, the developer, Potomac Investment Associates, went to court to force approval.

Circuit Court Judge Wiley R. Wright sided with the developer and ruled that off-site traffic problems could not be part of the council's consideration. The city has appealed that decision to the Supreme Court, and last night some council members warned the developer against rushing ahead with the project.

"I want it to be known if construction begins and we win appeal," said Democratic council member Donald Casey, "this member of council will be asking the builder to tear his building out of the ground."