June 30 (Reuters) - French catering and food services group Sodexo (EXHO.PA) on Friday raised the full-year outlook of its voucher business for the second time this year as it benefits from companies' attempts to get employees back to the office.

Employers have turned to companies like Sodexo and Edenred (EDEN.PA) to offer vouchers to staff as perks to encourage them to return to the office as well as help them cope with the rising cost of living.

"They beg us to work with them to help them bring employees back to the workplace with better, more diversified offerings," CEO Sophie Bellon said in a call with reporters.

Bellon said companies are using on-site services such as company canteens, and the chance use Sodexo vouchers to order lunch at nearby restaurants, to convince their staff of the advantages of office working.

Sodexo expects its voucher and benefits division, recently rebranded as Pluxee, to reach organic revenue growth of more than 20% in the year to the end of August, with an underlying operating profit margin exceeding 32%.

But the company's shares fell more than 2%, with analysts pointing to an "in-line" guidance raise and slow new business wins for the on-site services division. The shares are up about 11% year to date.

Sodexo's main division, which includes on-site services such as food, reported net new business contribution of close to 2% in the third quarter.

"We are in line with our expectation," finance chief Marc Rolland told analysts in a call.

Sodexo last raised its forecast for the voucher business in April, targeting organic growth close to 20% and an operating margin near 32%. It expects to spin off the business in 2024.

Sodexo also tweaked the group's full-year outlook, seeing an underlying operating margin of 5.5%, versus "close to" 5.5% previously.

Total group revenue was 6.03 billion euros ($6.55 billion) in the third quarter, slightly ahead of the 6.02 billion euros expected by analysts polled by the company.

($1 = 0.9201 euros)

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Reports on the French and Benelux markets from Gdansk. Previously worked at El Pais, as a freelance journalist based in Marseille for several Spanish-language news outlets and at the European Parliament in Brussels.