The decision has been made following comments made by Sky Sports presenters Richard Keys and Andy Gray about her being an appointed assistant referee for the Wolves versus Liverpool game last Saturday.
Mike Riley of the Professional Game Match Officals, who appoint referees and assistants to Premier and Football League matches said in a press statement: "PGMO & Sian believe that with any match the focus should not be on the officials but on the players & the game itself."
Keys and Gray, thinking their microphones were off, made a number of comments and were suspended by Sky yesterday and after further comments were made public, Gray was today sacked.
Barney Francis, managing director of Sky Sports, said in a press statement: "Andy Gray's contract has been terminated for unacceptable behaviour. "After issuing a warning yesterday, we have no hesitation in taking this action after becoming aware of new information today."