SEATTLE (AP) _ World trade delegates, seeking to salvage something from a miserable, protest-marred week, struggled Thursday for a compromise over deep differences that would allow them to launch a new round of market-opening negotiations.

While delegates at the 135-nation World Trade Organization sought to wrap up their talks by Friday, officials and businesses in Seattle were dealing with the aftermath of violent street protests in which demonstrators broke store windows, set fires and caused an estimated $2 million in property damage. There were 570 arrests.

A 24-hour curfew remained in effect for the area immediately around the giant convention center where the WTO talks were being held, an area that had the look of a war zone with several blocks of boarded-up store fronts where protesters had smashed display windows.

President Clinton, wrapping up a two-day visit in which police battled demonstrators within two blocks of his hotel, made one last appeal for the WTO to link trade agreements with basic protections of worker rights in the upcoming negotiations.

Speaking at a signing ceremony for a new international treaty banning abusive child labor practices, Clinton said the United States was committed ``not just to lower barriers but to raise living standards; to help ensure that people everywhere feel they have a positive stake in global trade that gives them and their children a chance for a better life.''

While some countries said the WTO might end up failing to launch even a scaled-down negotiating round, U.S. negotiators continued to express optimism that a way would be found to paper over huge differences that exist between countries.

The discussions, all taking place out of public view, alternated between four working groups dealing with specific issues and meetings of trade ministers from all 135 countries trying to sort out the progress being made.

The effort was expected to last through the night with exhausted delegates emerging with a final agenda for the talks on Friday.

``We are working very intensively. There is a great deal of activity,'' said Deputy U.S. Trade Representative Susan Esserman.

But U.S. officials conceded they were making little headway on Clinton's primary objective, to get worker rights included in the new round of discussions.

U.S. business groups complained that the president had made a tremendous blunder that set back his cause when he told the Seattle Post-Intelligencer in a front-page interview read by the delegates that the United States not only wanted agreement on a working group but would like to see that followed up by establishment of core labor standards. Clinton said violations of those standards should lead to trade sanctions.

The president's views went far beyond the administration's official negotiating position that all the United States was seeking was a working group to make an analytical study on the links between trade and worker rights.

Many Third World countries said Clinton's remarks confirmed their worst fears that the administration, bowing to pressures of American labor unions, would ultimately demand trade sanctions for their alleged labor violations as a way to take away their competitive advantage of lower wage levels.

``Our people don't get as much (pay) as someone in New York, but living standards are completely different,'' said Jose Guillermo Castillo, the economics minister of Guatemala.

``If Clinton pursues the labor issue, it may make us wonder, what's the point'' of even starting a new round, said Asmat Kamaludin, secretary general of Malaysia's ministry of international trade and industry. ``We cannot agree to the inclusion of labor in the WTO.''

Seattle city officials, who beat out 39 U.S. competitors for the right to serve as host for the WTO meetings, were still dealing with questions about whether they had been caught unprepared when a huge protest march on Tuesday turned violent _ and then over-reacted in the following days by firing tear gas at peaceful demonstrators and downtown office workers trying to catch buses home.

Embattled Mayor Paul Schell, at a news conference Thursday, offered apologies to innocent citizens who had been hit with tear gas or rubber bullets, saying the city was walking a fine line between enforcing its no protest zone and allowing normal business activities to continue.

``The lawful ones and the legal ones we want to help,'' Schell said.

Officials estimated that downtown businesses had lost $7 million in sales because of the violent protests on top of $2 million in property damage.