Singapore Airlines Cargo (SIAL.SI) has agreed to plead guilty in a US price-fixing case and pay a US$48 million ($63.4 million) criminal fine, the US Justice Department said on Tuesday.

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 US$48 million fine must be approved by the US District Court for the District of Columbia.

With Tuesday's 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 US$1.7 billion in criminal fines have been imposed, the department said.