Singapore Airlines Cargo has agreed to plead guilty in a U.S. price-fixing case and pay a $48 million criminal fine, the U.S. Justice Department said.

The cargo division of Singapore Airlines agreed to plead guilty to a single felony count for its part in the cargo price-fixing conspiracy, which has now ensnared 20 airlines.

The plea agreement and $48 million fine must be approved by the U.S. District Court for the District of Columbia.

With the plea agreement, the Justice Department has charged 20 airlines and 17 executives with price fixing in the air transportation industry. Four executives have been sentenced to prison, and more than $1.7 billion in criminal fines have been imposed, the department said.

The European Commission in Brussels has a related investigation, which imposed another $1.1 billion in fines on 11 airlines on Nov. 9 for the same conspiracy.

Airlines caught up in the probe include British Airways , Korean Air Lines , Qantas Airways , Cathay Pacific Airways , Air France , El Al Israel Airlines Ltd , Japan Airlines International and Nippon Cargo Airlines. (Reuters)