OTTAWA, OCT. 1 -- The Canadian government decided late tonight to resume trade negotiations Friday with the United States.

A spokesman for Prime Minister Brian Mulroney said the decision came after Treasury Secretary James A. Baker III made a new U.S. proposal that Canada felt "was sufficiently solid to go back to the negotiation."

"I want to say at this moment, we don't have an agreement," said Marc Lortie, Mulroney's press secretary. "There's still a long way to go and time is running short."

Lortie would not give details of the new offer that Baker made in telephone discussions with officials in Ottawa around 10 p.m. But he did acknowledge that it involved a proposal for a bilateral agency to resolve trade disputes between the two countries. Canada's chief demand in the 15-month-long talks has been for a binding tribunal that would exempt Canada from unilateral trade actions.

Mulroney was in Toronto today while his aides continued discussions. When he returned he approved the resumption of talks.

Canada had broken off formal negotiations but continued to have discussions with Baker and U.S. Trade Representative Clayton K. Yeutter.

The announcement came as a surprise because three top Canadian officials -- Finance Minister Michael Wilson, Trade Minister Pat Carney and Derek Burney, chief of staff to Mulroney -- left Washington for Ottawa earlier today without agreeing to restart the talks after a 2 1/2-hour meeting with Baker and Yeutter.

"We had another long discussion. We are returning to Ottawa to report to the Cabinet and a meeting with first ministers {provincial premiers} tomorrow {Friday}," Carney said. The meeting was the second high-level consultation that U.S. and Canadian officials had held in Washington this week in an attempt to get the talks restarted.

U.S. trade officials had been discouraged over the lack of any Canadian commitment to restart the talks despite their efforts.

The Canadian reluctance to return to the bargaining table seemed to reflect the deep divisions within that country over the free trade agreement, which was proposed by Mulroney 19 months ago.

Since then, the proposal has been attacked by opposition leaders and by labor unions who see it as a jobs issue, and cracks are appearing in the Mulroney government's support. The premier of the largest province, Ontario's David Peterson, is lukewarm at best over an agreement.

Canada walked out of the talks eight days ago, complaining that the Reagan administration has failed to address its key objective for a free trade pact -- the creation of a joint tribunal to settle disputes that has the power to shield Canada from U.S. laws against unfair trade practices.

Since then, the Reagan administration -- in a series of telephone calls and in the two sets of consultations -- has tried to come up with a formula that would meet Canada's concerns over being subject to what it sees as the capricious use of U.S. trade laws on its sales in the United States, while protecting American companies from unfair trade practices, such as Canadian subsidies.

On Capitol Hill, however, some members of House and Senate Committees dealing with trade expressed concern that the Reagan administration is giving too much to Canada in the high-level political consultations without getting anything in return.

House Ways and Means Committee Chairman Dan Rostenkowski (D-Ill.) was reported to have told Yeutter that he opposed making any concessions to the Canadians just to get them back to the bargaining table, sources said.

Lawmakers said Yeutter described the outline of the discussions with Canada "in vague terms," laying out what seemed to be a U.S. proposal to get Canada back to negotiations.

Business leaders who were briefed Wednesday by U.S. trade officials said they supported a free trade pact, which Harry Freeman, executive vice president of American Express Co., described as "an historic agreement" that could help the economies of both countries. He said the United States "had been very forthcoming" in meeting Canada's concerns, but added he was dismayed at how little time remained to conclude an agreement.

To get congressional approval under a fast track procedure that set a time limit for action and doesn't allow amendments or filibusters, President Reagan has until midnight Sunday to tell Congress he intends to sign a free trade agreement with Canada. While there may be some leeway in presenting the completed agreement to Congress, administration officials, Capitol Hill staff members and Canadian diplomats said that the broad shape of the pact has to be in hand by midnight Sunday in order to win congressional approval. Staff Writer Stuart Auerbach contributed to this report.