LONDON (Reuters) - British opposition leader Jeremy Corbyn was publicly lambasted by Scottish First Minister Nicola Sturgeon after declaring that his fight over the government's Brexit plan "starts now", shortly after he voted in favor of triggering Britain's EU exit.

Deep divisions have emerged within Corbyn's Labour Party over whether they should support the government's plan to trigger Brexit by the end of next month and pursue a clean break with the EU, or block the plan and fight for a softer Brexit.

Those differences came to a head late on Wednesday when 52 of Corbyn's 229 lawamkers defied his instruction that they should back the government. The government comfortably won approval for a law giving Conservative Prime Minister Theresa May the power to start the legal exit process.

"Real fight starts now," Corbyn tweeted after the vote. "Over next two years Labour will use every opportunity to ensure Brexit protects jobs, living standards & the economy."

The tweet inflamed many, including Sturgeon, who felt that the rallying cry had come too late and missed its mark.

"How?" Sturgeon responded on Twitter. "You've just handed the Tories (Conservatives) a blank cheque. You didn't win a single concession but still voted for the bill. Pathetic"

Other Twitter users seized upon Corbyn's message, posting mocking images of ill-fated attempts at resistance. Several expressed their dismay using pictures of the hapless Black Knight comedy figure in "Monty Python and the Holy Grail" who was unable to see when he was beaten.

Labour's support is divided between more prosperous urban constituencies that generally favored staying in the EU and declining industrial areas that strongly backed Brexit. To complicate things further, many pro-EU Labour lawmakers represent anti-EU areas.

(Reporting by William James; Editing by Toby Chopra)