Yemen's official news agency says the Shiite rebels have killed at least 20 people and detained dozens across the country's north since killing their top ally, former President Ali Abdullah Saleh.

The rebels known as Houthis appear to be escalating their crackdown on any possible sign of rebellion among their one-time allies from Saleh's party, the General People's Congress. They are also shutting down the internet and tightening an already existing media blackout.

According to SABA, the official news agency now under control of the internationally-recognized government, the Houthis also blew up 20 houses in the northern province of Hajja and replaced the province's governor who was a onetime Saleh associate.

The agency reported on Monday that the Houthis also arrested 49 people in Mahwet, another northern province in Yemen.