A US federal jury has ordered two media companies to pay $US1.2 million ($1.3m) to a freelance photojournalist for their unauthorised use of photographs he posted to Twitter.

The jury found Agence France-Presse and Getty Images wilfully violated the Copyright Act when they used photos Daniel Morel took in his native Haiti after the 2010 earthquake that killed more than 250,000 people, Mr Morel's lawyer, Joseph Baio, said.

The case is one of the first to address how images that individuals make available to the public through social media can be used by third parties for commercial purposes.

"We believe that this is the first time these defendants, or any other major digital licensor of photography, have been found liable for wilful violations of the Copyright Act," Mr Baio said in an email.

Lawyers for AFP and Getty did not immediately respond to requests for comment.

US District Judge Alison Nathan, who presided over the trial, ruled in January the two companies were liable for infringement.

An editor at AFP discovered Mr Morel's photos through another Twitter user's account and provided them to Getty.

The infringement was blamed on an 'innocent mistake'

The photos were then widely disseminated to Getty's clients, including several television networks and the Washington Post.

The trial was held solely to determine the amount of damages for Mr Morel, based on whether the jury found AFP and Getty wilfully infringed on his copyrights.

The $US1.2 million ($1.3m) was the maximum statutory penalty available under the Copyright Act, Mr Baio said. AFP had asked for the award to be set at $US120,000 ($130,000).

Several news outlets that published Mr Morel's images previously settled with the photographer for undisclosed amounts, including the Washington Post, CBS, ABC and CNN.

During the trial Marcia Paul, a lawyer for Getty, said Mr Morel was asking the jury "to make him the best paid news photographer on the planet".

Joshua Kaufman, a lawyer for AFP, blamed the infringement on an innocent mistake and said the Twitter user who posted the photos without attribution bore responsibility for the error.

The AFP editor, Mr Kaufman, said he believed the pictures were posted for public distribution.

AFP filed the lawsuit in 2010 against Mr Morel, seeking a declaration it had not infringed on his copyrights after Mr Morel accused it of improper use.

Mr Morel then filed his own counterclaims.

AFP had initially argued that Twitter's terms of service permitted the use of the photos.

But Judge Nathan found in January that the company's policies allowed posting and "retweeting" of images but did not grant the right to use them commercially.

Twitter to take steps to prevent surveillance of its users

Meanwhile, Twitter said it has implemented a security technology that makes it harder to spy on its users and called on other Internet firms to do the same, as Web providers look to thwart spying by government intelligence agencies.

The online messaging service, which began scrambling communications in 2011 using traditional HTTPS encryption, said it has added an advanced layer of protection for HTTPS known as "forward secrecy".

"A year and a half ago, Twitter was first served completely over HTTPS," the company said in a blog posting.

"Since then, it has become clearer and clearer how important that step was to protecting our users' privacy."

Twitter's move is the latest response from US internet firms following disclosures by former spy agency contractor Edward Snowden about widespread, classified US government surveillance programs.

Facebook Inc, Google Inc, Microsoft Corp and Yahoo Inc have publicly complained that the government does not let them disclose data collection efforts. Some have adopted new privacy technologies to better secure user data.

Forward secrecy prevents attackers from exploiting one potential weakness in HTTPS, which is that large quantities of data can be unscrambled if spies are able to steal a single private "key" that is then used to encrypt all the data, said Dan Kaminsky, a well-known Internet security expert.

The more advanced technique repeatedly creates individual keys as new communications sessions are opened, making it impossible to use a master key to decrypt them, Mr Kaminsky said.

"It is a good thing to do," he said.

"I'm glad this is the direction the industry is taking."

Reuters