MIAMI (AP) _ Coast Guard officials said Monday they knew nothing about a reported federal probe of drug corruption involving at least 11 guardsmen.

An NBC report Monday night said the corruption case was expected to go to a federal grand jury soon. The report cited unnamed sources as saying the case focused on a member of President Bush's Coast Guard protection detail in Maine and an officer stationed in Islamorada in the Florida Keys.

''We are trying to find out if there is such a thing,'' said Jim Simpson, the press secretary for Admiral Paul Yost, the Coast Guard commandant. ''All we have right now are NBC's allegations.''

Federal authorities said the two unnamed guardsmen, along with at least nine other present and former members of the Coast Guard, are under investigation for selling classified information to smugglers, NBC reported. Four members of the Coast Guard's Islamorada station were convicted in 1988 on drug charges involving four kilos of cocaine they allegedly seized in waters off Florida and sold to an undercover agent in North Carolina, the Coast Guard said.

Art Sola, Jeffrey Mey, Steven Vanheuson and James Weiss have been in prison since then, and Coast Guard officials said the case was closed, Simpson said.

''We knew about the guys who've been convicted, but as far as any pending cases, Admiral Yost was not aware of them,'' Simpson said. ''If they have evidence, they should bring an indictment and put guys in jail instead of leaking it through the press.''

Sources cited by NBC say the new indictments would be handed up as part of phase two of ''Operation Tempest.''