Detailed images taken by high-altitude U2s showed the balloon's equipment "was clearly for intelligence surveillance and inconsistent with the equipment onboard weather balloons," the senior State Department official said.

"It had multiple antennas to include an array likely capable of collecting and geo-locating communications," the official said in a statement.

"It was equipped with solar panels large enough to produce the requisite power to operate multiple active intelligence collection sensors," the official said, on grounds of anonymity.

A US fighter jet shot the balloon down over the Atlantic on Saturday after it had crossed much of the country, overflying areas where the US keeps nuclear missiles in underground silos and bases strategic bombers.

The incident led US Secretary of State Antony Blinken to cancel an imminent trip to Beijing that had been long in planning and aimed at improving communications between the two rival superpowers.

The official indicated that the US believes the balloon was under the control of the Chinese People's Liberation Army, and is part of a fleet of balloons that China has sent over more than 40 countries on five continents to collect intelligence information.

"We are confident that the balloon manufacturer has a direct relationship with China's military, " the official said.

The official said the US was weighing taking action against Chinese entities linked to the balloon's operation, which suggests it might slap them with sanctions.

Earlier Thursday Beijing confirmed that it refused an overture on Saturday by US Defense Secretary Lloyd Austin for phone discussions with Chinese counterparts over the balloon issue.

"This irresponsible and seriously mistaken approach by the US did not create a proper atmosphere for dialogue and exchanges between the two militaries," China's defense ministry said in a statement.

US operations meanwhile continued to recover debris from the balloon just off the coast of the eastern state of South Carolina.