Families of 9/11 victims should expect smaller compensation checks now that the federal government has increased the number of eligible cancer types to 50, Mayor Bloomberg said yesterday.

“Unless you believe the federal government is going to vote us more money — and I think to do that you probably have to believe in the tooth fairy as well — it looks like we have to deal with just this amount,” Hizzoner said.

“It’s just a finite amount of money.”

As The Post first reported on Sunday, the National Institute on Occupational Safety and Health has decided to expand the number of cancers covered by the $2.77 billion federal compensation fund, known as the Zadroga Act.

The official announcement was made yesterday.