SANAA, Oct. 24 (Xinhua) -- Yemen's Houthis have detained seven more UN aid workers in the capital Sanaa, taking them from their homes, a Houthi source told Xinhua on Friday.

"Four of them were detained tonight (Friday), while the rest were arrested yesterday (Thursday)," the source said on condition of anonymity.

On Wednesday, UN Special Envoy Hans Grundberg said in a statement that 12 UN international aid workers were flown out of Sanaa Airport after being released from Houthi detention.

According to several Houthi sources, the release was mediated by the foreign ministries of Iran and Oman, both of which maintain ties with the Houthi group.

Grundberg added that 53 UN staff members remain arbitrarily detained, alongside numerous aid workers and employees of NGOs and diplomatic missions.

The new arrests followed a televised speech last week by Houthi leader Abdulmalik al-Houthi on the group's satellite channel, al-Masirah, in which he accused UN aid workers of spying for Israel and aiding Israeli airstrikes in August that killed 12 senior Houthi officials.

The Houthis seized the capital Sanaa along with several northwestern provinces in 2014, triggering a devastating civil war and a dire humanitarian catastrophe that left millions of Yemenis dependent on foreign aid. ■