PHILADELPHIA — An insurer says a contractor being sued by people injured in a Philadelphia building collapse that killed six others had an invalid insurance policy.

The Philadelphia Inquirer reports (http://bit.ly/13FMLHH ) that Berkley Assurance Co. of Iowa filed a lawsuit Monday in Philadelphia Common Pleas Court. The company argues contractor Griffin Campbell misrepresented his history and details of the demolition.

Berkley also says Campbell's insurance policy expired May 1 because he and his firm failed to pay a premium. The company is asking the court to confirm that the policy is either canceled or void.

A message left for Campbell's attorney was not immediately returned.

The accident happened June 5 as the downtown building was being demolished. It collapsed onto a neighboring Salvation Army thrift store, killing two employees and four customers.