The latest spate of arrests came a day after a Spanish judge formally clubbed Alluni together with Usama bin Ladin and 33 others, charging them with "belonging to a terrorist group".
A source involved in the investigation said about five people had been arrested, with more arrests likely to follow.
"Some of those arrested have some relation to Taysir Alluni. They were people close to him," the source said.
They were arrested on the orders of High Court judge Baltasar Garzon from Valencia in eastern Spain and from Granada in the south.
Alluni had been holidaying in Granada before his current ordeal began on being arrested earlier this month.
Alluni has protested his innocence and his lawyer has described his arrest as a product of "western bias".
Aljazeera has also labelled Alluni's detention as an uninhibited attack on press freedom.
One of the Arab world's best known journalists, who gained fame by interviewing Bin Ladin and reporting from the battle zones of Afghanistan and Iraq, Alluni has been accused by the Spanish authorities of passing messages and providing money to al-Qaida operatives.