The union that represents Northwest Airlines ground workers and reservation agents filed suit against Delta Air Lines Monday in federal court over Delta's efforts to integrate worker seniority lists.

Northwest's ground workers are represented by the International Association of Machinists and Aerospace Workers while Delta's comparable workers are not unionized. Following the acquisition of Eagan-based Northwest by Atlanta-based Delta in late October, Delta asked leaders from the Northwest union to meet with a group of Delta employees and work out seniority list integration.

"We're not willing to negotiate" until the National Mediation Board has declared that a single airline exists, said Stephen Gordon, president of the IAM's District 143, which represents 12,500 Northwest employees. And when the union does negotiate, it will be with Delta executives, he said, not a committee of Delta employees.

A similar lawsuit was filed recently by Northwest's flight attendants' union.

In a statement Monday, Delta said the position taken by both unions "is wrong as a matter of law and does not serve the interests of our combined work groups."State launches heating aid Web site

The state of Minnesota has created a new Web site to help Minnesotans get information on heating assistance, winter safety tips and energy efficiency and conservation this winter.

The Stay Warm site at www.staywarm.mn.gov was created by the Office of Energy Security at the Department of Commerce with help from state agencies like the Department of Human Services, the state's major utilities and nonprofit organizations in the fields of energy and social services.