Riga - The Defence Ministry in the Baltic state of Latvia launched an enquiry Tuesday into the costly purchase of five minesweepers from the Netherlands after it emerged that the ships had been bought without instruction manuals.

"The items were purchased without instructions in a language which the user could understand," said a Defence Ministry statement.

More than a year passed from the purchase date in 2005 before English-language user manuals and technical documents were eventually acquired from the French navy, which operates similar vessels, a Latvian Armed Forces spokesperson told the German Press Agency dpa.

The extra paperwork cost 580,000 euros (820,000 dollars).

Defence Minister Imants Liegis said an internal investigation had turned up suspicions of "wasteful spending of public funds" and has called in the national anti-corruption force, KNAB, to help with further probes that may lead to criminal charges.

Four of the ships have already been bought and are on active service with NATO, but a fifth vessel would no longer be needed, Liegis ruled.

The investigation uncovered a host of irregularities in the purchase of the Alkmaar-class vessels, each with a price tag of 11.4 million euros.

Inexperienced staff were put in charge of the deal and no market research was done into the current market price of a used minesweeper. (dpa)