The head of Turkey's armed forces says the military will respond with greater force if shelling from Syria continues to spill across the border.

General Necdet Ozel gave the warning Wednesday during a visit to the Turkish border village of Akcakale, where cross-border shelling killed five people last week. Turkey responded with six days of retaliatory artillery fire into Syria.

At an Organization of Islamic Cooperation meeting in Istanbul, Turkish Prime Minister Recep Tayyip Erdogan criticized the Syrian government, saying its actions are “hurting the heart of humanity and the whole Islamic world.”

Mr. Erdogan said there are 99,000 Syrian refugees in his country now, and he expects more to cross into Turkey to flee the violence between Syrian government and rebel forces.

Meanwhile, U.S. officials say the U.S. military has sent 150 planners and specialists to Jordan to help with a surge of Syrian refugees. The team is also preparing for other possible developments, including a widening of the conflict and the potential that Syria will lose control of its chemical weapons.

The task force is based at a military outpost north of the Jordanian capital, Amman. The New York Times reported the mission began after the United States organized a training exercise in Jordan in May involving troops from 19 countries.

Jordan is a U.S. ally, and Jordan's King Abdullah was the first Arab leader to call for Syrian President Bashar al-Assad to step down after the uprising against his rule began in March 2011.

The United Nations said earlier this month Jordan was hosting more than 100,000 Syrian refugees.

In Britain, authorities say they have arrested two people as part of an investigation into travel to Syria in support of “alleged terrorist activity.”

British police arrested a man and a woman late Tuesday at London's Heathrow Airport, but did not disclose their nationality.

British Foreign Secretary William Hague said in a television interview there is evidence of foreigners, including people from Britain, traveling to Syria to join the nearly 19-month conflict. He declined to give further details about the Tuesday arrests.