Six German cement producers have been fined a record €660 million as part of an investigation into price-fixing.

Germany's competition authority, the Federal Cartel Office, said yesterday that it had levied its highest-ever fines on companies including Readymix, HeidelbergCement, Alsen and three others.

Readymix received the smallest fine of €12 million after co-operating with the authorities.

However, HeidelbergCement, the market leader in Germany, was fined €251.5 million. The company said it would appeal the penalty.

Mr Ulf Böge, president of the Federal Cartel Office, said the six companies had "almost completely eradicated competition in the \ sector" by carving up the German market between them as early as the 1970s.

Their illegal activity enabled them to set prices at levels "that would have been impossible in conditions of free competition", he said.

"These firms knew what they were doing. In my opinion, the guilty parties should admit that the fines are moderate," he added.

Mr Böge justified the fines, saying the companies' illegal practices had caused untold damage to customers and consumers, as well as to the wider economy.

The office decided to investigate the sector after receiving complaints from companies in the construction sector that the price of cement remained stable despite economic fluctuations.

Investigators raided the offices of 38 companies last July and established that, since the 1970s, the concrete companies eliminated competition by buying up cement works simply to close them down.

The companies continued the practice in eastern states following German unification in 1990.

Other documents seized in the raid showed how the companies hindered cement imports and divided the market between them into geographical areas.

HeidelbergCement said it rejected "most of the charges and denies having made additional profits" from the pricing practices.

According to a spokesman, the company would appeal the fine but he added that the company had set aside in its accounts an "appropriate" sum to cover the fine.

The size of the fines was calculated based on sales volume and the degree to which they co-operated with the authorities.

Company employees who organised and operated the cartel have been levied with fines totalling €1.5 million.

It was initially estimated that the companies would be fined more than €1 billion, but that was before the firms began aiding the authorities in their investigations.

Other companies fined were Schwenk Zement (€142 million), Dyckerhoff (€95 million), Lafarge Zement (€86 million) and Alsen (€74 million).