Four websites run by the U.S. National Oceanic and Atmospheric Administration have been compromised in recent weeks, the agency said on Wednesday.
NOAA, the part of the U.S. Department of Commerce that includes the National Weather Service, "deflected" the attacks, the agency said in a statement. Some services were down for unscheduled maintenance but were restored as of Wednesday afternoon, the agency said.
"These effects did not prevent us from delivering forecasts to the public," NOAA said in the statement. The agency's investigation of the breach is not finished, the agency said.
Chinese hackers were suspected in the attack, according to a Washington Post story, but a NOAA spokesman declined to talk about the source of the attack.
The announcement from NOAA comes just days after the U.S. Postal Service announced a breach that potentially compromised the personal information of 800,000 employees, as well as some customers who contacted the government service. Chinese hackers were also suspected in the Postal Service attack.
The intrusion at NOAA happened in late September, but the agency didn't indicate it had a problem until about a month later, the Post story said. The NOAA breach prompted cybersecurity teams to seal off information related to disaster planning, aviation and other sensitive topics, the Post said.
Grant Gross covers technology and telecom policy in the U.S. government for The IDG News Service. Follow Grant on Twitter at GrantGross. Grant's email address is email@example.com.