UNITED NATIONS (AP) — Secretary-General Ban Ki-moon called for an immediate halt to hostilities in Yemen Tuesday as the U.N. Security Council held an emergency meeting on the chaotic situation in the impoverished Middle East nation.

Violence has gripped Yemen's capital, Sanaa, since Monday and has been described as a coup. Yemeni authorities say Shiite Houthi rebels are shelling the presidential residence and have raided the presidential palace.

U.N. spokesman Stephane Dujarric said Ban deplores the heavy fighting between armed groups and Yemeni presidential guards throughout Sanaa and "calls on all sides to immediately cease all hostilities, exercise maximum restraint, and take the necessary steps to restore full authority to the legitimate government institutions."

Britain's U.N. Ambassador Mark Lyall Grant said he called Tuesday's closed-door council meeting to hear a briefing on the situation from the U.N. envoy to Yemen, Jamal Benomar, who is in Qatar and heading to Sanaa later Tuesday.

"Clearly the situation has deteriorated very significantly over the last 48 hours and that's why the Security Council needs to meet and decide its response," Lyall Grant said.

He expressed hope that the council will issue a statement expressing "deep concern about the deteriorating security situation."

The secretary-general urged all sides to resolve differences through peaceful means and to remain engaged with U.N. and Gulf Cooperation Council members, Dujarric said.

Ban condemned the Jan. 17 kidnapping of presidential adviser Ahmed Awadh Bin Mubarek and called for his immediate release.