Switzerland's financial watchdog has said London-based Laxey Partners breached Swiss law in acquiring a 22.89 per cent stake in Swiss construction company Implenia.

The Federal Banking Commission in Bern said it was filing a criminal complaint with the Swiss finance ministry, claiming Laxey had not properly disclosed its holding.

In a statement, the commission said that Laxey had placed Implenia shares with other parties, allowing it to retain voting control over the shares for several years.

This is considered an "indirect share acquisition" subject to disclosure obligations under Swiss law.

Implenia, which has rejected a hostile bid from Laxey, said the British firm had "deliberately and knowingly" violated Swiss rules through its "indirect and clandestine stake-building" using a network of five unnamed Swiss and European banks.

Switzerland's largest construction firm, formed from the merger of Zschokke and Batigroup in 2006, said Laxey now faced fines of up to SFr250 million ($244.9 million) and suspension of all its Implenia voting rights for several years.

Laxey has replied that it would appeal against the commission's ruling. "We see this decision by the banking commission as a political decision," commented Laxey director Roger Bühler.

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