A strike by musicians has closed 18 musicals playing on New York's Broadway.

The dispute between musicians and producers concerns the guaranteed minimum number of orchestra staff employed in each theatre's orchestra pit. The producers have suggested 15 but the American Federation of Musicians wants 24. The previous contract between the two sides expired last week.

It had been hoped to present the shows using recorded or computer-generated sound but actors and stage crew were not prepared to cross musicians' picket lines.

Productions such as Beauty and the Beast, Chicago, Les Miserables and The Lion King are amongst those affected by the action. Cabaret, where a different contract is in place, is running as normal, as are plays without music and off-Broadway shows.

According to the League of American Theatres and Producers, surveys have shown that Broadway generates $4.4bn in revenue annually for New York.