* July 1 deadline for Norway's oil wage talks
* Fields produce 17-18 pct of Norway's output -Reuterscalculation
* Further escalation likely unless deal found (Updates ExxonMobil's comment)
By Stine Jacobsen and Terje Solsvik
OSLO, June 27 (Reuters) - About 755 Norwegian workers onseven oil and gas fields could go on strike from Saturday,hitting output from western Europe's top producer, if a new wagedeal is not agreed before a Friday deadline, trade unions saidon Monday.
A final round of mandatory talks will be hosted by a statemediator on June 30 and July 1 in an effort to avoid disruptionthat could start the following day.
The affected fields account for nearly 18 percent ofNorway's oil output and a little more than 17 percent of itsnatural gas, Reuters calculations show.
Combined oil output was about 285,000 barrels per day in thefirst four months of the year, with natural gas output at 48.5million cubic metres (mcm) per day.
Norway currently produces about 1.6 million barrels of crudeand 280 million standard cubic metres of natural gas per day.Its combined natural gas liquids (NGL) and condensate output isabout 400,000 barrels.
Employers have argued that a plunge in oil prices since 2014must be accompanied by cost cuts and flexible work practices tohelp to keep the industry competitive.
Unions, meanwhile, say that members should receive payincreases matching those in other industries.
The Industri Energi union said it would take out 524 membersif the talks break down, affecting the Statoil-operated Oseberg, Gullfaks and Kvitebjoern fields.
The SAFE union said it would take out 156 workers onExxonMobil's Balder, Jotun and Ringhorne fields.
In addition, 75 workers on Engie's Gjoea fieldwould also go on strike, the smaller Lederne union said.
Engie said it would shut Gjoea in the event of a strike,while ExxonMobil said a strike would affect its operations.
Statoil declined to comment.
A protracted conflict could ultimately result in more than7,400 workers going on strike, data from the state mediator'soffice showed.
"We do, of course, wish for mediation to lead to a deal, sothat conflict is avoided," SAFE said in a statement.
The three labour unions will negotiate on behalf of the oilworkers, while Norwegian Oil and Gas (NOG) will represent thecompanies.
In 2012 a 16-day strike among some of Norway's oil workerscut the country's output of crude by about 13 percent and itsnatural gas production by about 4 percent. (Additional reporting by Nerijus Adomaitis and Henrik Stolen;Editing by Louise Heavens, David Goodman and David Evans)
