U.S. Senator Chuck Grassley's Twitter account was hacked on Monday with bogus tweets attacking his stance on Internet anti-piracy legislation, his office said.

Grassley, an Iowa Republican and prolific tweeter, had at least eight false tweets posted as he was on a flight heading from Iowa to Washington, spokeswoman Jill Kozeny said.

His staff noticed his Twitter account had been broken into a few minutes after the first false tweet was posted and called Twitter to have the password changed, his office said in a statement.

Kozeny said one of the fake tweets said: Dear Iowans, vote against ACTA, SOPA, and PIPA, because this man, Chuck Grassley, wants YOUR internet censored and all of that BS.

Grassley is the ranking Republican on the Senate Judiciary Committee, and the bogus tweets dealt with legislation aimed at halting Internet piracy.

Grassley was among sponsors of the Protect IP Act, or PIPA,

but pulled his support for the anti-piracy measure last week.

The incident has been reported to the Senate Sergeant at Arms, the statement said.

(Reporting By Ian Simpson; Editing by Greg McCune)