A senior Home Ministry official said Prime Minister Abd Allah Ahmad Badawi, who is also Home Minister, signed the extension orders, the New Straits Times reported.
The seven are detained under the controversial Internal Security Act (ISA), which gives police sweeping powers and allows for indefinite detention without trial.
Home Ministry officials could not be reached for comment.
The extension brought to 13 the number of detainees with suspected links to Islamist groups who had their detention
extended over the past week, the report said.
Malaysia is holding the suspects under the ISA, after a series of arrests dating back to before the 11 September 2001 attacks on the United States.
A large number of them are believed to be members of Jemaah Islamiah, blamed for bombings in Indonesia and the Philippines, including the night club blasts that killed 202 people on Indonesia's resort island of Bali in October 2002.