36 people have died and 123 injured after two passenger trains collided near Alexandria in Egypt.

Authorities said a train from Cairo ploughed into the back of another train which was waiting at a small station in the Khorshid district, just west of Alexandria.

The stationary train had just arrived from Port Said, a city on the northern tip of the Suez Canal, according to the Egyptian Railways Authority.

One passenger, Moumen Youssef told Reuters news agency: "The train I was riding was going very quickly. I found myself on the floor. When we came out, we found four train cars crushed and a lot of people on the ground," he said.

Bodies lay strewn on the ground as crowds of people gathered around the carriages where some passengers were still trapped.

The accident, which occurred at 2.15pm, is believed to have been caused by a track switching error.

All hospitals in the region have been placed on high alert as emergency services continue to attend to the injured at the scene.

The public prosecutor has ordered an urgent investigation Sky News reports.

Egypt train crash
Egyptian security forces stand guard at the site of a train collision in the area of Khorshid, in Egypts Mediterranean city of Alexandria, on August 11, 2017AFP/Getty