WASHINGTON — The Justice Department is helping British authorities investigate the hacking of climate scientists' emails, which caused an uproar among skeptics of global warming when they were released two years ago.

Ten days ago, the Justice Department contacted the San Francisco web development company Automattic, asking it to preserve records of three climate skeptic bloggers in the U.S., Canada and United Kingdom who recently received another batch of stolen emails from a server in Russia.

The Justice Department declined to comment on the nature of the investigation and did not give Automattic a reason for its request. But the letter to Automattic suggests the request is part of an ongoing investigation by law enforcement officials in the United Kingdom.

On Dec. 14, detectives from the Metropolitan Police in London and members of the Norfolk Constabulary raided the home of Roger Tattersall, the British blogger "Tallbloke." The Norfolk Constabulary's jurisdiction in east central England includes the University of East Anglia, where scientists' email accounts were targeted. Tattersall was not arrested, but police confiscated two laptop computers and other equipment, according to his blog.

Those who dispute that the earth is going through a dangerous warming trend have pointed to quotes from emails of leading climate scientists about their research and dismissive comments about those who doubt global warming. Skeptics see the emails as evidence of a broad conspiracy to convince the public of global warming.

In one email from October 2009, Benjamin Santer, a climatologist at the Lawrence Livermore National Laboratory in California, wrote to another scientist in England about climate skeptic Pat Michaels:

"I'm really sorry that you have to go through all this stuff. Next time I see Pat Michaels at a scientific meeting, I'll be tempted to beat the (expletive) out of him. Very tempted."

Every independent panel that has looked into the emails, however, has cleared the scientists of allegations of falsifying data. The Justice Department's request to preserve records for the three blogs — Tallbloke, Climateaudit and JeffId — covers a period from Nov. 21 to Nov. 23, 2011, when a link to the new set of emails appeared in the comments section of each site, said Steve McIntyre, a Canadian mining industry consultant who devotes most of his time to Climateaudit.

The first set of stolen emails appeared in similar fashion in 2009, almost to the date, as governments prepared to attend the United Nations climate talks in Copenhagen. The new emails, posted on a Russian server like the first batch, appear to have been stolen in 2009 and came out this time in the run-up to global climate talks in Durban.