Contract negotiations between the University and Local 26, representing Harvard's dining hall workers, resumed yesterday after a month-long hiatus, with a session both sides called constructive.

Although Harvard made no concrete counterproposal to the union's demands, both Edward W. Powers, associate general counsel for employee relations, and Fred Walden, vice president of Local 26, said yesterday the meeting "opened up a dialogue" between the two parties."

The union and the University, which broke off bargaining after the initial session April 9, have another meeting slated for Tuesday.

The union's list of demands includes a 20-per-cent wage raise, improved fringe benefits and additional holidays.

Powers asked for a provision in the contract to pay part-time workers less, a source at the meeting said.

"I think the negotiations are going to be long and tough," Edward B. Childs, chief shop steward for the dining hall workers, said yesterday.

Although Powers would not discuss a possible counterproposal, sources said he will probably offer a 27 per cent wage increase spread over three years. This plan resembles the recent agreements between the University and the Harvard Union Employees Representative Association, the Harvard Police Association, and the Maintenance Trade Council.

Dining hall workers voted down such a plan last March.

Walden said he expects negotiations to proceed smoothly from now on. "Powers has a good rapport with the negotiating committee at this point," he said.

When talks broke down last month, Powers labeled the union's demands "unrealistic" while union members termed Power's attitude "hostile."

The present contract expires June 19. Once the University presents a concrete offer, union negotiators will take it back to the rank-and-file for a vote.

Powers declined to comment on his strategy for Tuesday's meeting