At least 16 people have died after armed men stormed an Ivory Coast beach resort.
A spokeswoman for the Foreign Office said there was no indication at this stage that any Britons had been caught up in the incident, but reports said Ivorian officials confirmed two of the casualties were French and German nationals.
The Ivory Coast's president Alassane Ouattara said 14 civilians and two special forces operatives, as well as six attackers, were killed in the attack on three hotels in Grand-Bassam, a popular weekend destination for both Ivorian nationals and foreigners.
The beach setting of the incident - about 25 miles east of Ivory Coast's economic centre Abidjan - bears a resemblance to the attack in the Tunisian resort of Sousse last June in which 30 Britons were among 38 tourists killed.
Meanwhile, officials said a car bombing in Turkey's capital Ankara killed more than 30 people and wounded around 75 others.
Prime Minister David Cameron tweeted: "I'm appalled by the devastating terror attacks in Ankara and the Ivory Coast. My thoughts are with all those affected."
French minister for foreign affairs Jean-Marc Ayrault said on Twitter that France remained fully mobilised against terrorism.
Ivorian footballers led tributes to the victims.
Manchester City midfielder Yaya Toure wrote on his Facebook page in both French and English.
He said: "It is with a heavy heart that I learnt of the tragedy that befell my country on Sunday afternoon. I am saying prayers for all the mourning families and offer comfort and support to the Ivorian population.
"Equally, the president of the republic who made the effort to manage the situation for the tranquillity and peace in the Ivory Coast. May God watch over the Ivory Coast."
Bournemouth footballer Max Gradel tweeted: "May God protect my lovely country in this hard moment Cote D'ivoire".
The historic town of Grand-Bassam is a Unesco World Heritage site.
Foreign Office travel advice for the country warns against all but essential travel to certain parts of the country.
It says: "There is a high threat from terrorism. You should be vigilant after recent attacks in Mali and Burkina Faso. Attacks could be indiscriminate, including in places visited by foreigners."
For Grand-Bassam, the website says people should check travel advice before travelling.
The advice was updated on February 9 and was still said to be current on March 13.
A group that monitors jihadist websites said al Qaida in the Islamic Maghreb has claimed responsibility for the attack in Ivory Coast.
Witness Marcel Guy saw at least four gunmen with Kalashnikov rifles on the beach. He said one approached two children, and spoke in Arabic.
One child knelt and prayed, but the other was shot dead.