A weeklong strike in Oakland ended Monday night after a mediation session concluded between representatives for the city and its largest union, allowing major services to resume Tuesday morning with city workers back on the job.

Negotiators for the city and the labor group spent eight hours Monday holed up in separate conference rooms in the Marriott Hotel in downtown Oakland, bringing point-by-point contract terms to their go-between, David Weinberg, a former Federal Mediation and Conciliation Service commissioner.

No deal resulted from the first of what could be many mediation sessions, but union leaders said it restored their optimism and faith in the bargaining process.

LATEST SFGATE VIDEOS

Now Playing:
  • Now Playing
    Free things to do in San Franciscosfgate
  • Handout Video: Brushwood Estate Lake Tahoesfgate
  • How to stay safe around mountain lionssfgate
  • The Regulars: The Performersfgate
  • Charter bus overturns on Hwy. 101 in SFsfgate
  • Fun facts about Bay Area celebritiessfgate
  • San Diego Fire Department's footage from the Lilac Firesfgate
  • Google Earth tour of San Franciscosfgate
  • Spiked Eggnog Custard With Rum-Caramel Popcornsfgate
  • Whole Foods' first 365 store opens in the Bay Areasfgate

After seven months of negotiations, some 3,000 members of the Service Employees International Union Local 1021 walked off the job Dec. 5 and picketed outside City Hall, forfeiting a week’s worth of pay to protest what they said were the city’s unfair labor practices and bad-faith bargaining.

Although the city’s emergency services have been operating, the strike shut down street cleaning, road repairs, libraries, child care centers, senior care centers, building inspections and other city services.

Lawyers for the city filed complaints with the state Public Employment Relations Board alleging the strike was unlawful. On Monday night, Mayor Libby Schaaf said she was pleased the work stoppage was over.

“We are so grateful to the Oakland residents for their patience as we have gone through this week without our valuable city services,” she said. “We are so happy that Oakland is getting back to work.”

City Administrator Sabrina Landreth, who was in the mediation session, said the “healthy dialogue” was “respectful, professional and productive.” She said the parties reached an agreement around working conditions, but didn’t go into details.

Any deal that emerges from mediation, set to resume Monday, will need approval from SEIU members and the City Council.

The striking SEIU workers were joined by 1,000 members of International Federation of Professional and Technical Engineers Local 21, who also gave up their pay. The two groups, and other Oakland employees who refused to cross the picket line, represent well over half the city workforce.

All were expected to return to work Tuesday. Some who work overnight shifts were clocking in at 11 p.m. Monday.

Many employees were returning to steep backlogs of work — but Felipe Cuevas, a heavy-equipment mechanic for the Public Works Department and SEIU chapter president, said the workload was nothing new.

“You work overtime until your body can’t do it anymore,” he said. “Then you rest. And then you go back and you do it again as asked. We’re so understaffed.”

The dispute between SEIU and the city is focused on the second half of a two-year contract, as well as on noneconomic issues, like working conditions and the city’s use of temporary part-time employees. The two sides agree on first-year terms, which include giving workers a 4 percent wage increase, retroactive to July 1, when the union’s last contract expired.

The city’s most recent offer, made Thursday, would guarantee a 1 percent raise in the second year and give an additional 1 percent if certain revenue targets are met.

The SEIU countered with a request for a 4 percent increase in the second year of the contract, with wages increasing by 1 percent in each quarter. The city rejected the proposal Friday and declared an impasse.

The Oakland strike, described as “indefinite” when it began last week, was different from most walkouts by public-sector unions, which typically have a timetable for returning to work, said Fred Glass, who teaches labor history at City College of San Francisco and previously worked as spokesman for the California Federation of Teachers.

“It’s a signal that the union is very serious about this. The workers are willing to make a sacrifice,” Glass said Monday before the strike was halted. “Given the great and growing economic inequality, particularly in the Bay Area, I wouldn’t be surprised if we were to see more militant activities by working people attempting to keep up with the cost of living.”

Kimberly Veklerov is a San Francisco Chronicle staff writer. Email: kveklerov@sfchronicle.com Twitter: @kveklerov