Turkey's president says its incursion into the Kurdish-held enclave of Afrin in Syria is progressing "successfully" and will continue until the last "terrorist" is eliminated. Recep Tayyip Erdogan said Turkish troops and allied Syrian fighters have killed at least 268 Syrian Kurdish fighters since the operation against Afrin was launched on 20 January. He said Turkish troops have suffered two losses.

However, Rami Abdulrahman, director of the Syrian Observatory for Human Rights, said 48 Turkey-backed Syrian fighters with Free Syrian Army groups had been killed. And the death toll among the Kurdish YPG was so far at 42, he said.

Turkey Syria Kurdish Afrin
Turkish artillery near Hassa shell People's Protection Units (YPG) positions over the Syrian border on 21 January 2018 Bulent Kilic/AFP

The Turkish ground and air offensive on Afrin, codenamed "Operation Olive Branch", has raised tensions in the already-complicated Syrian conflict and threatened to further strain ties between Turkey and the US. Turkey says it aims to create a 30-kilometre (20-mile) deep "secure zone" in the Kurdish-controlled enclave on its border.

Turkey views the main Syrian Kurdish militia in northern Syria as a threat because of its links to Kurdish insurgents fighting in southeastern Turkey. The Kurds are the main US ally against Islamic State (Isis) in Syria, and played a key role in driving the extremists from much of the country's northeast. The US has urged Turkey, a Nato ally, to exercise restraint.

However, Erdogan has promised to expand the operation, threatening to push farther east to the town of Manbij to the east, which Kurdish fighters liberated from Isis in 2016. Erdogan said in Ankara that his country will "not take a step back". He repeated his criticism of Washington's support for the Kurdish militia, saying the US should have partnered with Turkey in fighting Isis.

Turkish troops and allied Syrian fighters are pressing ahead with their operations in Afrin, approaching from three sides. Afrin is surrounded by Turkish-backed Syrian fighters, Turkish troops and Syrian government forces. The only road out of the enclave to government-controlled Aleppo has been closed by the Kurdish militia for security reasons.

But Turkish forces and its Syrian allies are meeting stiff resistance from the Kurdish militia. On Tuesday (23 January), the People's Defence Units (YPG) regained control of a village breached by Turkish forces. Turkish forces were also repelled from a hill they seized a day earlier on the eastern edge of the district. Kurdish militia spokesman Nureddine Mehmud said the YPG and allied militias had managed to prevent the Turkish forces from making "any real progress" in Afrin.

Activists say Turkey has mobilised about 10,000 Syrian fighters to storm Afrin, with some stationed in Azaz, on the eastern edge of Afrin, and others to the south in Atmeh. There are an estimated 8,000 to 10,000 Kurdish fighters in the enclave, home to about 800,000 civilians.

The United Nations says an estimated 5,000 people have fled the fighting. The UN says the displaced fled from areas near the border but are still inside the enclave. Authorities in Afrin have ordered the closure of exit points with surrounding areas, and are only allowing people to enter from Syrian government-held areas to the south, according to the UN.

At least 27 civilians, including eight children and four women, have been killed in the fighting in Afrin, mainly in Turkish airstrikes, according to the Syrian Observatory for Human Rights, a Britain-based group that monitors the civil war.

Turkish officials say 11 rockets launched from Syria have landed in Turkish towns along the border, killing at least one Syrian refugee and injuring 47.

Rezan Hiddo, a Kurdish official in Afrin, said people are seeking shelter wherever they can find it. "The strikes are from aircraft, rocket launchers and artillery," he said. "This is causing townspeople to take cover in basements. People in the villages are hiding in their farms, while those in the mountains are taking cover in caves for protection."