WikiLeaks, the pet project of embattled whistleblower Julian Assange, has derided his jail sentence as "vindictive" and expressed concerns over the upcoming hearing on his possible extradition to the United States. 

"Julian Assange's sentence is as shocking as it is vindictive," the organisation tweeted on Wednesday. "We have grave concerns as to whether he will receive a fair extradition hearing in the UK."

Earlier in the day, the 47-year-old WikiLeaks co-founder was sentenced to 50 weeks in prison by a UK court for violating his bail conditions in 2012. Back then, he was facing extradition to Sweden over allegations of rape, which he branded as politically motivated. While the rape investigation into Assange was dropped five years later, last month Swedish prosecutors reportedly received a formal request to re-open the case.

Fearing that an extradition to Sweden was a pretext for his eventual transfer to the United States, where he could be charged with espionage for leaking thousands of classified documents on diplomatic communications and US-led wars in Afghanistan and Iraq, he skipped bail and sought refuge in Ecuador's embassy in London for the following seven years. Ecuador revoked his asylum on 11 April, and the same day the Australian-born journalist was arrested inside the embassy by police.

Westminster Magistrates' Court is due to hear a separate request by the United States to extradite Julian Assange for the disclosure of military and diplomatic secrets. The US Justice Department accuses him of conspiring with former army intelligence analyst Chelsea Manning in a bid to gain access to a government computer as part of a 2010 leak of US military reports. Manning in 2017 was sentenced to 35 years in jail for handing over internal secretive documents to WikiLeaks.