The assaults by the Shi'Ite militia hit camps for forces of the internationally recognised government in the provinces of Marib and Hadhramaut, the officials said.
They spoke on condition of anonymity because they were not authorised to speak to the media.
The attacks were a major escalation since a de-facto truce in Yemen in April 2022 that halted major fighting between the Iranian-aligned Houthis and a Saudi-led coalition, which backs the internationally recognised government.
Yemen's army reported attacks by Houthi fighters on its camps, leaving dead and wounded among troops, but it did not provide a death toll.
The Houthis did not comment on the attack but said that a statement would be released shortly on a "major" military operation, without elaborating.Â
Yemen has been embroiled in a civil war since 2014, when the Houthi rebels seized the capital of Sanaa, forcing the internationally recognised government into exile in Saudi Arabia.
A Saudi-led coalition intervened months later and has been battling the rebels since 2015 to try and restore the internationally recognised government to power.
However, the war has turned into a stalemated proxy conflict with neither side winning.
Houthi fighters have also recently attacked several Saudi ships or forced them to change course.
with DPA
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