SAN FRANCISCO — Accused of overcharging the government for court-authorized surveillance, Sprint Communications Inc. is defending the integrity of its bills.

In a complaint filed in the U.S. District Court for the Northern District of California in March, federal prosecutors alleged that the telecommunications company marked up its bills to law enforcement agencies by 58 percent. But Sprint fired back on Friday, insisting that civil charges under the False Claims Act fall short because its invoices accurately detailed the services it provided.