PORTLAND — The Maine Department of Marine Resources has issued its first red tide warning of 2010, banning the harvesting of mussels and surf clams from Harpswell to the New Hampshire border.

Red tide has been a growing problem with major outbreaks in three of the past five years. Red tide taints clams and mussels, making them unsafe for people to eat.

State officials already warned of the prospect of widespread red tide outbreaks this spring and summer that could force hundreds of miles of clam flats to be closed.

Rep. Chellie Pingree of Maine said she’s sponsoring a bill that includes, among other things, more funding for next-generation buoys that can monitor for red tide.