A corporate jet that has been used by Argo Group International Holdings appears not to have flown for more than two months since it became a talking point in a proxy battle between the company and activist shareholders Voce Capital Management LLC.

Flight logs during the past three years show that the 20-seat jet was used regularly every month until February 16 when it touched down in Chicago, at which point publicly available flight details stopped.

Eleven days later, Voce launched its proxy battle with a letter to shareholders of Bermudian-based Argo, claiming the company has a “spendthrift culture” and misdirects corporate assets to support the chief executive officer’s “lifestyle and hobbies”.

Voce, a San Francisco-based hedge fund, is the beneficial owner of about 5.6 per cent of the shares of Argo. It is seeking the removal of a number of Argo’s directors, and has put forward nominees to replace them. Argo responded to Voce’s claims on April 15, appealing to shareholders to support the board at the annual meeting on May 24. In a statement, it said Voce’s claims were “poorly researched” and had “little regard for the truth”.

Yesterday, in a counter-response, Voce included further questions together with a link to a flight log for a G-5 corporate jet, which it has estimated costs the company $3 million per year.

Voce said: “Shareholders will notice that the G-5 doesn’t appear to have flown a single time since the publication of our shareholder letter, which would be the longest stretch it has ever sat idle during Argo’s control of this asset.

“Either Argo has found a way to cloak these embarrassing flight logs, or else perhaps its extensive prior use was not, in fact, for legitimate purposes, as we suspect. Once again, we call upon Argo to solve the mystery for shareholders.”

The aircraft is owned by Jetaway Air Service. Argo has previously stated that the plane was also used by third parties unrelated to Argo at various times during periods referenced by Voce. The Royal Gazette sent inquiries to US-based Jetaway and Argo asking why the plane appears to have been inactive for the past two months.

In a statement issued last night, Argo accused Voce of making “misleading statements”. It added that “the flight log Voce refers to is for an aircraft that was neither owned by Argo, nor exclusively used by Argo. Lastly, when our executives use corporate aircraft for personal trips, they do so at their own expense”.

Voce had asked five questions in its release yesterday. The activist investor asked whether Argo “truly believes” that the company’s stock price moving in tandem with peers justifies “the misuse of corporate assets, including a fleet of three aircraft and a global network of corporate housing, for personal use by its CEO?”

It also wanted to know what percentage of flights on corporate aircraft were used to transport Mark Watson, the CEO, for personal purposes or a mix of personal and professional travel.

Voce also asked why Argo does not disclose the exact amounts it spends on its various sponsorships, “so shareholders can assess whether they constitute a ‘modest cost’ as the company argues”. It mentioned a series of yacht regattas, and land and ocean racing teams, that Argo has sponsored.

In addition, Voce asked: “Why will Argo not come clean about its corporate housing programme?” It claimed it has discovered three corporate apartments in Miami Beach, Florida that Argo either owns or appears to have acquired, and noted that while Argo has refuted having a penthouse apartment above its offices in New York City, it has previously referenced having corporate housing in New York.

Argo responded: “Like so much of Voce’s poorly researched narrative, this latest representation is simply wrong. The properties identified in Voce’s press release are not corporate housing, but rather part of our investment property portfolio: they are income-producing assets purchased in connection with a Section 1031 like-kind real estate exchange following the sale of a commercial property in California.”

Argo added that the company had spent on average less than $1 million per year over the past five years for named sponsorships. The company added: “We are committed to an open and constructive dialogue with all our investors.”

Voce said it will release a detailed plan next week “outlining how to unlock significant additional value at Argo by dramatically improving operations and capital allocation”.