CAIRO, Dec 16 (Reuters) - Yemen's Houthi rebels said on Wednesday the Saudi Arabia-led military coalition was not adhering to a United Nations-sponsored ceasefire.

Brigadier General Sharaf Luqman, a spokesman for Yemen's armed forces allied with Houthi fighters, said that a "serious escalation by land, sea and air is taking place by the alliance in various areas," according to the Houthi-controlled Saba news agency.

A ceasefire took hold in Yemen on Tuesday as United Nations-sponsored peace talks opened in Switzerland in a new push to end months of fighting that has killed killed nearly 6,000 people and dragged in foreign powers.

Luqman said that strikes from the sea were currently taking place on Hodaida and in Taiz there were attacks by ground troops while air strikes by the Arab coalition had not stopped.

"We will not stay hand-tied but we will respond strongly towards the breaches that are taking place by the alliance and their mercenaries," Luqman said.

(Reporting by Ali Abdelatti, Writing By Maha El Dahan; Editing by Cynthia Osterman) ((Maha.Dahan@thomsonreuters.com; +9712-408-2101; Reuters Messaging: maha.dahan.thomsonreuters.com@reuters.net))

Keywords: YEMEN SECURITY/