Flagship carrier Korean Air posted a second-quarter net loss after the US Department of Justice fined the company for its involvement in price collusion.

The US justice department on Wednesday announced that Korean Air had agreed to pay a $300 million fine for its involvement in a price-fixing scandal affecting both passenger and cargo prices on US routes.

British Airways was also fined $300 million in relation to the collusion and other carriers are still being probed.

Korean Air will pay the $300 million fine to the justice department over the next five years, but reflected it in the second-quarter results.

The world's largest cargo carrier by freight volume posted a net loss of US$232 million in the June quarter, shifting from a net profit of $16.15 million a year earlier.

However, second-quarter operating profit rose 9.3 percent to $81.73 million from $74.79 million and sales climbed 8.9 percent to $2.28 billion from $2.09 billion.

In the January-June period, Korean Air reported a net loss of $90.62 million, swinging from a net profit of $154.14 million a year earlier.

But operating profit for the six months rose 42 percent to $245.85 million from $173.55 million, while sales were up 9.8 percent to $4.48 billion from $4.08 billion.

Korean Air is also being investigated by the country's anti-trust authorities for alleged price fixing on Korean routes, which is linked to the US probe and the one in the EU.