An analyst has recommended shareholders of William Hill reduce their holdings in the company following the unofficial strike action which started last Sunday.

William Hill holds 71% of the WHO joint venture with Playtech. About 180 employees walked out of the Tel Aviv office on Oct. 16 over concern that the company was seeking to transfer the functions to the U.K. or Gibraltar. In addition 100 employees in the WHO Bulgarian centre walked out, and in Manila, 300 Playtech workers involved with WHO activities also walked off the job.

"Last Sunday matters came to a head when Henry Birch, WHO's chief executive, and Jim Mullen, its chief operating officer, visited Tel Aviv only to find staff had been redirected to a local beach," media reports suggest.

"When Mr Mullen visited the Tel Aviv office, he was locked out. Its email and telephone systems were also taken down,"

William Hill confirmed that Eyal Sanoff the chief marketing officer of the U.K. bookmaker’s William Hill Online marketing team in Tel Aviv had resigned and other senior managers were subject to disciplinary action in connection with “disruption” in offices there and in Manila and Bulgaria.

According to the Telegraph Sanoff resigned after William Hill told him to provide day-to-day access to the computer systems of the Tel Aviv operation.

For several months he allegedly refused to comply, and the company gave him a September 30 deadline. Three days before that deadline expired, Sanoff quit, leaving the issue open to speculation that all was not as it should be in Tel Aviv.

However the company claimed “Consumer-facing websites” had not been directly affected by the problems, and managers in Tel Aviv were “working through these issues.”

Analyst, Ivor Jones of Numis Securities, said a walkout could have “material impact” on the growth of William Hill’s online operations.

“This could leave WHO without its key marketing growth engine for some time,” Jones wrote in a note to investors. He lowered his recommendation to a “reduce” today from “hold” “Even if the current situation is quickly resolved, we believe it serves to highlight the uncertain future for WHO.”

Shares in the company dropped 5.3 percent or 12.7 pence closing at 228.8 pence in London.

“The vast majority of employees of the marketing team in Tel Aviv have good working relationships with the business and with colleagues across William Hill Online,” a statement from the company said “William Hill Online is committed to its sales and marketing operation in Tel Aviv and contrary to media reports has no intention of relocating this operation.”