ADEN An unidentified warplane attacked the presidential palace in Aden on Thursday after rival forces fought the worst clashes in years in Yemen's second city, an official and residents said, in a sharp escalation of the country's months-long conflict.
Thirteen people were killed when forces loyal to President Abd-Rabbu Mansour Hadi fought their way into Aden's international airport and wrested an adjacent military base from a renegade officer, Aden governor Abdulaziz bin Habtoor said.
Both the fighting on the ground and subsequent air attack appeared to be part of a deepening power struggle between Hadi and the Shi'ite Muslim Houthi group, which controls the capital Sanaa and is allied with former president Ali Abdullah Saleh.
In a statement Hadi described the attack on Aden as an attempted coup backed by the previous regime.
"The failure of the military coup... was backed by the former regime, which was one of the perpetrators of extermination," said the presidential statement.
The statement made no reference to Saleh but said that "agents of Iran" had also backed the former regime's forces.
"What happened today is a clear message to the whole world that the coup and their supporters of traitors reject any solutions or sit at the dialogue table in order to exit the crisis of Yemen to safety," it added.
Earlier on Thursday in a televised speech, Habtoor accused the Houthis of being behind the air attack on the compound in Aden's al-Maasheeq district, where Hadi is based, but said the bomb "had fallen harmlessly into the sea".
"Aden is peaceful and things are back to normal after the rebellion was ended," he said on Aden television. A Houthi spokesman could not immediately be reached for comment.
The Houthis earlier this week removed the air force chief for refusing to provide them with air support and replaced him with a general who is closer to their group.
Residents said anti-aircraft guns opened fire at the plane, and smoke was seen rising from the area, but it was not immediately clear if Hadi was in the compound. A second approach by a warplane was repelled by anti-aircraft fire, they said.
An aide to Hadi said the president was "safe at a secure location ... There was a raid, but there were no casualties."
In Washington, U.S. State Department spokeswoman Jen Psaki called on both parties to refrain from violence.
"We're concerned about actions that could increase tensions in Yemen and lead to further destabilization. We call on all parties to de-escalate the situation," she said.
The affiliation of the aircraft was not immediately known, but residents in Sanaa said they saw an unusually busy level of flights by military aircraft in the skies of the capital.
Earlier in the day, soldiers and militiamen loyal to Hadi using tanks and armored vehicles battled their way into Aden's airport and stormed the nearby military base, residents said.
General Abdel-Hafez al-Saqqaf had been holed up for days in the base after refusing Hadi's order to hand his Special Forces unit to another officer's command, a security source said.
The fighting brought traffic at the airport to a halt.
Witnesses said many Special Forces soldiers had been taken prisoner at the al-Sawlaban base in the Khor Maksar district.
Saqqaf later turned himself in to the governor of the adjacent Lahj province, the Aden al-Ghad newspaper reported.
In a statement, the Houthi-led Supreme Security Committee urged an end to the Aden fighting, saying both sides "are obliged to keep the peace and return to the negotiating table".
The growing instability in Aden has overshadowed a determined campaign of attacks by al Qaeda, long seen by Washington as the main threat to the country, which shares a long border with the world's top oil exporter, Saudi Arabia.
Tensions have been heightened in Aden since Hadi fled there in February after escaping a month of house arrest in Sanaa by Houthi forces who seized Sanaa last September. Hadi has been trying to consolidate his control over Aden, the better to mount a challenge to Houthi ambitions to control the country.
(Additional reporting by Mohammed Ghoabri in Sanaa, Noah Browning in Dubai and Doina Chiacu in Washington; writing by Sami Aboudi, Editing by William Maclean and John Stonestreet)