The managing director of building supplies group Readymix has resigned and will be replaced in the short term by a former senior executive from Cemex, the ultimate parent of the group.

According to a statement to the Irish Stock Exchange, Joe Doyle resigned as managing director and board member by "mutual agreement" and with immediate effect. No specific reasons were given for the decision by the company or Mr Doyle.

Pending the appointment of a full-time successor, Roger Gonzalez, a senior finance executive who has worked with Cemex for several years, will be taking over. He is currently finance director of Readymix, having taken over that position in August following the resignation of Frank Lynch.

Readymix is 76 per cent owned by RMC Group, which last year was acquired by Mexican concrete products firm Cemex in a £2.3 billion (€3.38 billion) deal. Cemex is the third-largest cement producer globally.

Market observers have speculated for some time about RMC/Cemex's intentions. Some sources suggest that Cemex executives want to take the company private, but no decision has been made on this.

Some market sources believe Cemex is looking to increase its control over the company, but Readymix has other powerful shareholders like property developer Gerry Gannon. Bank of Ireland also holds nearly 12 per cent of the stock on behalf of its clients.

The Readymix statement said the "interim management team will continue to drive the implementation of a range of performance improvement measures and initiatives approved by the board earlier this year".

Chairman Adrian Aer said the fortunes of the company were improving. "Our plans to reshape the business, to reduce costs and improve margins are progressing apace. The board is confident the interim management arrangements announced today and the increased operational and regional focus will provide a strong platform on which to build."

Mr Doyle succeeded John Machinery as managing director of Readymix in January 2004, having been a senior executive with the company since 1998.

The company issued two profit warnings in 2004. This year, operating profits dropped by 23 per cent in the first half as price competition and higher costs ate into margins.

Mr Gonzalez joined Cemex in 1996. Before that, he worked for Shell Oil in Central America and the Nicaraguan Central Bank.