Rocket attacks on the southern Turkish province of Kilis killed three people, the Dogan news agency reported Saturday, as German Chancellor Angela Merkel heads to neighbouring Gaziantep later in the day.
Turkey has blamed previous rocket strikes on Islamic State fighters in neighbouring Syria.
Four rockets struck Kilis city, near the border with Syria, on Friday, the provincial governor's office said.
The rockets had been fired from territory under control of Islamic State forces in northern Syria, Dogan reported. Islamic State is fighting Syrian rebels, including factions backed by Turkey, in the area.
On Monday, at least five Syrians - four of them children - were killed in Kilis by rocket fire.
Kilis is one of the regions hosting the most refugees from the Syrian civil war. Some 130,000 refugees have arrived in the city, which had 90,000 inhabitants before the war broke out five years ago, officials say.
Merkel, European Council President Donald Tusk and European Commission Vice President Frans Timmermans are scheduled to arrive Saturday afternoon in Gaziantep.
They are set to visit a refugee camp with Turkish Prime Minister Ahmet Davutoglu.
The trip was originally planned a week earlier and was supposed to include Kilis, but the security situation led to a change in plans.
Meanwhile, the state run Anadolu news agency reported that six members of an alleged Islamic State cell were arrested in Konya, a province in central Turkey.
The report said the alleged cell members were scouting locations for a possible suicide bombing. The arrest took place a day after Davutoglu visited Konya, his home province.