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Hani Mohammed, Associated Press
Yemenis chant slogans during a protest against caricatures published in French magazine Charlie Hebdo in front of the French Embassy in Sanaa, Yemen, Saturday, Jan. 17, 2015.

SANAA, Yemen — Shiite Houthi rebels abducted the chief of staff to Yemen's president early Saturday in the center of the capital, Sanaa, starkly highlighting the unrest plaguing the Arab world's poorest country.

The rebels, who have taken over large swaths of Yemen, claimed responsibility for kidnapping Ahmed Awad bin Mubarak. In a statement, they said they abducted him to disrupt a meeting scheduled for the same day that was to work on a new constitution and the reorganization of the country into federally organized regions.

"We will not allow this draft resolution to pass," they said, referring to a reform agreement made last year to divide the country into six regions. They had previously rejected the plan.

Officials said gunmen kidnapped bin Mubarak and his two guards when they stopped their car in central Sanaa. They spoke on the condition of anonymity because they were not authorized to brief journalists.

One of the youngest politicians in Yemen, 46-year-old businessman-turned-political figure bin Mubarak emerged during the uprising that forced longtime leader Ali Abdullah Saleh to step down in a U.S.-backed agreement.

The Houthis seized large areas of Yemen, including Sanaa, last year as part of their protracted power struggle with President Abed Rabbo Mansour Hadi.

Critics say the Houthis are a proxy for Shiite Iran, charges the rebels deny.

Bin Mubarak is personally at odds with the Houthis. He was the president's choice for prime minister last October, but his nomination was derailed after the Houthis opposed him for his ties to the president.

Meanwhile Saturday, thousands demonstrated in central Sanaa against the Shiite rebels in a protest called by civil society groups. They marched to the Defense Ministry, chanting: "Revolution against the Houthis! Revolution against terrorism!"

A separate protest in front of the French Embassy saw demonstrators express their outrage over the satirical Paris newspaper Charlie Hebdo's cartoon depictions of the Prophet Muhammad.