PARIS (Reuters) -French payments company Worldline has hired auditing firm Accuracy to assess its remaining portfolio of merchants engaged in risky activities, it said on Wednesday.

Last month, a group of 21 European media outlets alleged that Worldline covered up client fraud to protect revenue. Belgian prosecutors said last week they had opened an investigation into potential money laundering activities at its Belgian unit.

In response to the media reports, Worldline said that since 2023 it had strengthened merchant risk controls and terminated non-compliant client relationships.

In addition to hiring Accuracy, consultancy Oliver Wyman will also be brought in to review Worldline's control systems, the group said in a statement.

Initial findings from the reviews will be published on July 30 with first-half results, while the main conclusions will be made public when Worldline reports its quarterly earnings on October 21.

"By the end of October, we expect any potential weaknesses and improvement areas to be identified, and in such cases, necessary action plans will be executed to ensure optimal operational integrity," the company said.

Worldline, one of Europe's biggest payments processors by transactions handled, saw its market value shrink by over 500 million euros ($590 million) after the allegations.

Shares in the Paris-listed company have partly recovered since, trading at 3.93 euros apiece by 1347 GMT after hitting a record-low price of 2.69 euros on June 25.

The yield on Worldline's 2030 bond, which it issued in June to raise 550 million euros, has risen by 40.8% in seven days, highlighting investors' fretting.

($1 = 0.8501 euros)

(Reporting by Sudip Kar-Gupta and Gianluca Lo Nostro;Editing by Dominique Patton, Joe Bavier, Peter Graff)