Most of Detroit's public schools are closed for the day after the teaching union urged members to call in sick following a weekend announcement that the district will not be able to pay school staff from this summer.

Detroit is eligible to shed billions in debt in the largest public bankruptcy in US history, a judge said in a long-awaited decision that shifts the case toward how the city will accomplish that task.

The city of Detroit has gone to court in an attempt to be declared bankrupt, despite protests from workers and pension funds.