The halt of oil transfers onto tankers began on Tuesday and was lifted on Thursday, officials said on Thursday.

It was part of "a continuing effort to ensure the security of our homeland," consistent with Code Orange, the second-highest alert level the United States has been at since 21 December, said Russ Knocke, a Department of Homeland Security spokesman. 

"Right now we are allowing tanker traffic throughout the port," Lt. jg Latarsha McQueen of the Coast Guard's Valdez Marine Safety Office said. "Appropriate safety measures are being taken with regard to the security information that we have." 

Code orange

It was not clear what specifically triggered the decision
to suspend the traffic. Valdez is the terminal for the trans-Alaskan pipeline from Prudhoe Bay. The 800-mile (1,280-km) pipeline normally carries about 1 million barrels a day to Valdez, or about 17% of US domestic production. 

The United States remains at Code Orange - the second-highest level on a five-step "terror attack" warning scale. 

Mike Heatwole, spokesman for pipeline operator Alyeska
Pipeline Service Co, said the shutdown of tanker loading did
not interrupt production. 

Alyeska is owned by oil companies with interests on Alaska's North Slope. Major owners are BP, ConocoPhillips and Exxon Mobil.