UPDATE 1-Civilian toll in Ukraine climbs to 227 dead, 525 injured -U.N.

(Adds U.S. secretary of state comments on civilian toll)

GENEVA, March 2 (Reuters) - The United Nations human rights office said on Wednesday that it confirmed 227 civilians had been killed and 525 injured in Ukraine through midnight on March 1 following Russia's invasion of its neighbour.

In Washington, U.S. Secretary of State Antony Blinken said the Russian assault was causing damage to non-military targets but did not outright say Moscow was deliberately targeting civilians.

"We're looking very closely at what's happening in Ukraine right now including what's happening to civilians. We're taking account of it, we're documenting it and we want to ensure, among other things, that there's accountability for it," Blinken told reporters.

The U.N. human rights office said in a statement that most of the casualties were caused by the use of explosive weapons with a wide impact area, "including shelling from heavy artillery and multi-launch rocket systems, and air strikes."

It said it believes the true toll in the week-long conflict is "considerably higher", especially in government-controlled territory, due to reporting delays in some areas where fighting has been most intense.

The invasion has yet to achieve Russian President Vladimir Putin's aim of overthrowing Ukraine's government but it has sent more than 870,000 people fleeing to neighbouring countries and jolted the global economy as governments and companies line up to isolate Moscow. (Reporting by Stephanie Nebehay in Geneva and Humeyra Pamuk in Washington; Editing by Grant McCool)