Broadway has been thrown into turmoil with more than 20 hit plays and musicals including The Lion King and Mamma Mia were forced to close because of strikes by disgruntled stagehands. The protestors, who are responsible for moving scenery and equipment, set up picket-lines in front of theatres in New York on Saturday. The strike comes after three months of negotiations between producers and a union about pay and working conditions failed to produce an agreement. No new talks are scheduled and it is unclear how long the strike will last. All but eight Broadway shows have been shut down and producers say they plan to pay refunds to people who have bought tickets for cancelled shows. It comes at a time that is traditionally one of Broadway’s busiest of the year. New York mayor Michael Bloomberg warned on the economic consequences of the action. He says, "While this is a private labor matter, the economic impact is very public and will be felt far beyond the theatres closed today." The Broadway strike comes in the wake of a separate screenwriters’ strike which began in Hollywood last week, prompted by a disagreement over royalty payments.