Armed al-Houthi rebels attacked an UN humanitarian relief convoy in northern Yemeni province of Jawf, injuring a UN employee, the state-run Saba news agency reported on Friday. General director of medical care of Jawf province Hussein Abu Hadra said the rebels opened fire at the UN relief convoy on Thursday when the aid staff from UN, the United Nations Children's Fund (UNICEF) and UN World Food Program (WFP) were offering assistance to about 400 displaced families in al-Mabdah camp. These families moved from Amran province and Saada province due to the confrontations between the Yemeni army and al-Houthi rebels there since August. Abu Hadra said some armed citizens nearby exchanged fire with the rebels, according to the report. Meanwhile, general director of public health office in Jawf province Hussein al- Ghanimi said 'the al-Houthi sabotage elements' aimed to hinder local and international relief efforts. The injured UN staff has been admitted to hospital intensive care in the capital, he said. Al-Houthi rebels have been launching intermittent wars against the troops and thousands of people, soldiers and insurgents have been killed in Saada province since 2004, according to Saba news agency. On Aug. 11, the Yemeni government launched a major offensive against the al- Houthi rebels aimed at uprooting the uprising, forcing tens of thousands of people to leave their homes. 