Human Rights Watch has urged Turkey to allow Syrians displaced by government shelling to cross the border to safety.

It says the Syrian army hit two migrant camps on April 13 and 15, triggering an exodus of 3,000 people.

Last week, the rights group said Turkish border guards had shot at Syrians escaping an Islamic State offensive. Turkey, home to 2.7 million Syrian refugees, rejects the claim and says it has an open-door policy toward migrants, but new arrivals are rare.

Rights groups have repeatedly slammed a new Turkey-EU deal to curtail the flood of refugees into Europe, raising questions about the safety of Syrian refugees on both sides of the Turkish border.

The rights group says tens of thousands of civilians are trapped along Turkey's border.