The structure on a barge in San Francisco Bay that appears to be a twin of one built on a barge in New London is linked to Google, CNBC is reporting.

A Coast Guard spokesman in California told CNBC, "We can confirm that Google is involved or associated with" the barge, but said he couldn't say more because of a nondisclosure agreement.

That barge is reportedly owned by the same company as the barge that was in New London before it was towed to Maine earlier this month, and reports have contained speculation that the similar structures on both barges could be floating data centers owned by Google.

The Day reported Sept. 28 that no one involved with the construction in New London harbor would say or even knew the mysterious structure's purpose. The four-story building, apparently made up of container units, attracted attention all summer.

Lt. Jeff Janaro, spokesman for Coast Guard Sector Long Island Sound, said Wednesday he could not say whether Google was involved with the structure built in New London.

"The Coast Guard is currently working with the owners of the barge to exercise our regulatory authorities as we do on many different types of vessels," he said in a statement. "Due to issues of commercial confidentiality, we are unable to disclose any more information at this time."

Janaro said he could not provide any additional information. The Day is waiting for the Coast Guard to respond to a Freedom of Information Act request filed Sept. 27 for documents related to the Coast Guard's review of the plans when the barge was in New London.

Turner Construction leased space at the Admiral Harold E. Shear State Pier in New London from Logistec USA sometime around May to build the structure on the barge, but never told Logistec exactly what it was building.

Two barges of equal size docked at the pier and container units to make up the building were brought in. A tugboat from Portland Tugboat LLC led the barge down the Thames River Oct. 9, en route to Maine.

In Portland, Cianbro Corp. will install undisclosed technological equipment inside the building, according to the Portland Press Herald.

The barges have drawn national media attention because of their similarities and Google's rumored involvement. Google has not commented on the matter.

j.mcdermott@theday.com