The German Federal Cartel Office is also believed to have imposed similar fines on up to another 50 concrete companies involved in the investigation.
Six of the companies involved in the investigation into allegations of market sharing were subsidiaries of RMC's main German business, Readymix.
In a brief statement to the London Stock Exchange, RMC said four senior employees working at its subsidiaries also received fines totalling more than pounds 81,000. Three of the workers had already resigned from their jobs as a result of the inquiry, while the fourth remained working at the group's CM subsidiary. None of the workers was named by RMC.
A spokesman for RMC said lawyers for the company were examining a 70- page report prepared by the German officials and considering launching an appeal. "Clearly, it's a disappointment to have a set-back like this and obviously we regret the fines," he said. "We have taken steps so that it will not occur in the German market or any other market again."
RMC has two weeks to appeal against the findings. The inquiry, which began in May, also included major cement companies such as Germany's Dyckerhoff and Holderbank and French group Lafarge.