An explosion that leveled the offices of an Arlington towing company Sunday night and critically injured one man may be linked to a recent undercover drug operation, Alexandria police said yesterday.

The crystal City Towing service, located at 2827 Jefferson Davis Hwy., had loaned one of its tow trucks to Alexandria police on "two or three occasions" during the course of a three month undercover investigation, according to Sgt. Al Levesque, head of the city's vice-narcotics unit.

The investigation led last week to indictments against 17 men accused of illegal drug activities.

Arlington police and fire officials declined to comment on the blast yesterday except to say that it is under investigation and that the same site was "firebombed" a year ago. The officials said they could not elaborate

The business is owned by William A. Konek, a 30-year-old former district policeman, and former roommate of Alexandria police officer George Branton. It was through that connection that arrangements were made to use the tow truck, according to Alexandria police.

The undercover operation involved a veteran Arlington police officer, Reginald Tillery, who successfully infiltrated the drug rings allegedly working out of Alexandria's Rte. 1 corridor, bounded by Wythe and Cameron streets.

The blast critically injured Mark Logan, an employee of another towing service, who was in the building when it blew up. Logan is listed in critical condition in the intensive care unit of Washington Hospital Center's burn unit with second- and third-degree burns over 60 to 70 percent of his body.

Levesque said employees of the towing company were aware that police were using the vehicle for undercover purposes.