Willy Selten, the owner of meat wholesaler Willy Selten BV, was detained on suspicion of fraud and forgery for his alleged involvement in false labelling of meat products.
Authorities also detained another former manager of the company, which prosecutors said processed 300 tonnes of horsemeat from suppliers in the Netherlands, Ireland and Britain between 2011 and 2012.
The meat was falsely identified in the Dutch company's records as beef and wrongly labelled as beef, a public prosecutor's statement said.
Selten is one of the two Dutch companies involved in the trading of 50,000 tonnes of beef that was recalled in April over suspicion it contained horsemeat. The meat was sold between January 2011 and January 2013.
Willy Selten appeared on Dutch TV on Wednesday evening and admitted his company mixed horsemeat with beef, but said it had been at the request of a client. He denied it was falsely labelled.
Earlier this month, the Dutch Economic Affairs Ministry said in a letter to the parliament that Selten had sold the meat to 132 companies in the Netherlands and 370 companies in 15 European countries. It did not say which countries were involved.
After contacting all suppliers, the Dutch food safety authority said last week the meat had ended up at 1,722 hotels, restaurants and caterers, 39 butchers, 184 supermarkets and 290 traders, warehouses and processing plants.
The Dutch recall is the largest since the horsemeat scandal broke in January, when horse DNA was found in frozen burgers sold in Irish and British supermarkets.
France found more cases of illegal horsemeat in beef products than any other country, results of official DNA tests ordered in the wake of the scandal showed, with more than 1 in every 8 samples testing positive.
