The European warrant from Sweden is being processed by the Serious Organized Crime Agency and will be sent to the Metropolitan Police, the BBC reported.
Assange is wanted in Sweden on sexual assault charges that he denies.
The British government Monday condemned WikiLeaks for publishing secret U.S. diplomatic cables that reveal sensitive sites and factories in Britain.
Security officials said the sites, including pipelines and communications and transport centers, could now become terrorist targets. The locations listed, from Cornwall to Scotland, include satellite communications sites and places where trans-Atlantic cables make landfall.
Arms factories involved in joint programs with the Americans are listed, along with a marine engineering firm in Edinburgh termed "critical" for nuclear-powered submarines.
Home Secretary Theresa May said all government departments have been ordered to carry out a security review.