A vehicle carrying police officers pulled up at the entrance of the prime minister's official residence, where a clutch of protesters called for Netanyahu to resign over the investigations.
Police declined immediate comment, but Israel Radio said Netanyahu was being questioned over allegations he awarded regulatory favours to Bezeq Telecom Israel in return for favourable coverage on a news site the company's owner controls.
Netanyahu, who has been questioned twice before in so-called Case 4000, and Bezeq have denied wrongdoing.
In February, police recommended Netanyahu be charged with bribery in two other cases. Israel's attorney-general is still weighing whether to indict him.
In the first investigation, known as Case 1000, he is suspected of bribery over gifts from wealthy businessmen, which police say were worth nearly $300,000.
The other, Case 2000, involves an alleged plot to win positive coverage in Israel's biggest newspaper by offering to take measures to curtail the circulation of a rival daily.
Despite the probes, the right-wing leader's popularity has risen in the past few weeks, a reflection, commentators said, of his tough security policies, U.S. withdrawal from the Iran nuclear deal he opposes, and the opening of the American Embassy in contested Jerusalem, a move Netanyahu has long advocated.
The surveys predicted that Netanyahu's Likud party, which heads a coalition largely comprised of right-wing and religious factions, would add up to four seats to the 30 it already holds in the 120-member parliament if an election were held now.
Israel is due to hold its next national ballot no later than November 2019.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)