The US military plans to widen its surveillance and firepower in conflict zones worldwide, including in Ukraine and the South China Sea, with a major expansion of US drone flights, the Wall Street Journal reported.

The Pentagon plans to increase daily flights by 50 per cent over the next four years, expanding them from 61 a day now to as many as 90 by 2019, the Journal said in its report late Sunday, citing senior defence officials.

Increased flights could also be used in other areas such as Iraq, Syria and North Africa, the paper said.

Reuters could not immediately confirm the report, and representatives for the Pentagon could not be immediately reached for comment.

Unmanned drone flights can be used on reconnaissance missions to gather video, photos and other surveillance data. They can also be used to launch air strikes, which has been controversial under President Barack Obama.

Under the phased-in plan, the US Air Force would continue to launch 60 drone flights a day, the Army would dispatch 16 and the Special Forces Command could contribute up to four, according to the newspaper. As many as 10 non-strike flights a day would come from private government contractors, it said.

There were no immediate cost estimates for the plan from Pentagon officials, the Journal said. - Reuters