(Adds comments from conference call, details on sanctions)
WASHINGTON, Aug 8 (Reuters) - Washington said on Wednesday it would impose fresh sanctions on Russia after it determined that Moscow had used a nerve agent against a former Russian agent and his daughter in Britain.
A senior State Department official said it had notified the Kremlin of the sanctions earlier in the day.
Sergei Skripal, a former colonel in Russia's GRU military intelligence service, and his 33-year-old daughter, Yulia, were found unconscious in the southern English city of Salisbury in March after a liquid form of the Novichok type of nerve agent was applied to his home's front door.
State Department spokeswoman Heather Nauert said it had been determined that Russia "has used chemical or biological weapons in violation of international law, or has used lethal chemical or biological weapons against its own nationals."
The sanctions will cover sensitive national security goods, a senior State Department official told reporters on a conference call, citing the 1991 Chemical and Biological Weapons and Warfare Elimination Act.
There would, however, be exemptions for space flight activities and areas covering commercial passenger aviation safety, which would be allowed on a case by case basis, the official added.
The official said a second batch of "more draconian" sanctions would be imposed after 90 days unless Russia gives "reliable assurances" that it will no longer use chemical weapons and allow on-site inspections by the United Nations.
"If those criteria are not met - it is up to Russia to make that decision - a second round of sanctions ...will to be imposed," the official said, "They are in general more draconian than the first round."
The news came as Republican U.S. Senator Rand Paul said on Wednesday he had delivered a letter from President Donald Trump to Russian President Vladimir Putin proposing cooperation. (Reporting by Lesley Wroughton; editing by Jonathan Oatis and Sandra Maler)