The NBA came down hard on Miami Heat owner Micky Arison on Monday, fining him $500,000, according to league sources, after he used his Twitter account as a sounding board about the lockout last Friday.

The league did not issue an official announcement, but an NBA spokesman confirmed to ESPN.com that Arison had been fined.

The $500,000 fine, first reported by Yahoo! Sports, is five times the amount other owners have previously been fined for public comments about the ongoing labor situation.

According to multiple league sources, commissioner David Stern was lobbied by some of Arison’s fellow owners to levy the stiff fine. Arison and several of his peers have been at growing odds as the lockout has deepened — a rift which spilled over into cyberspace last week.

Arison sent out a series of tweets from his verified account following the latest breakdown in talks between owners and players.

– Reported by Brian Windhorst of ESPN.com