* Grillo says some 5-Star senators lied over secret vote
* Signs of division appear in anti-establishment party
* 5-Star senator defends vote, says ready to resign if needed
Beppe Grillo, leader of Italy's 5-Star Movement, accused parliamentarians in his group who defied party orders over a secret ballot of lying and told them to "take the consequences", sparking furious online debate among his followers.
In the first sitting of parliament since February's inconclusive election, a handful of Senators from the anti-establishment 5-Star Movement cast their ballots with the centre-left in an election to choose the new speaker, despite instructions to cast a blank vote.
In a post on his blog late on Saturday night, Grillo said 5-Star parliamentarians were bound to follow voting directions agreed by a majority in advance and indicated that he expected any members who failed to do so to resign.
"If anyone has not met this obligation, they have lied to voters and I hope they will take the necessary consequences," he said. He said he wanted 5-Star senators to declare their votes.
Whether the implied threat is carried out or not remains to be seen but it underlines the challenge Grillo, who is not in parliament himself, will face in controlling his group from a distance.
More than 10,000 people commented on the post, with opinions split between those accusing him of acting like a dictator and others accusing rebels who voted with the left in choosing anti-Mafia judge Pietro Grasso as Senate speaker of betrayal.
The fiery ex-comic, who has come down heavily on followers who have defied him in the past, has frequently been criticised for his authoritarian streak, prompting former prime minister Silvio Berlusconi to say his movement was "like Scientology".
He refuses any deal with the mainstream parties which he says are indistinguishable from each other and equally responsible for driving Italy into crisis.
However the incident highlighted tensions in the movement, which draws heavily from a generation of young Italians much less willing to accept direction from any leader, a point which emerged clearly from much of the online commentary.
"Stop talking rubbish, Beppe. What do you want? To be some kind of long-distance Duce?" wrote Diego G, referring to the wartime fascist dictator Benito Mussolini. "Who do you think you are? The 'divine' interpreter of the popular will?"
Others however were much harsher on the dissenters and there were plenty of comments supporting Grillo. "They have to respect the rules of the movement. Kick them out," wrote Gionata T.
On Sunday, Giuseppe Vacciano, one of the senators who disobeyed instructions, defended his decision to vote for Grasso and said he was ready to resign if necessary.