Fearing a second blast, police cordoned off the area around the bus stop as medics tended to the injured [Reuters]

Seven people have been injured after a bomb placed on an electric bicycle exploded at a bus stop in Istanbul, police and local officials say.

The explosion occurred close to a police training school and a shopping mall in the Etiler district on Thursday, police said. Several ambulances were dispatched to the scene.

Seven people were injured by the blast, Huseyin Avi Mutlu, Istanbul's governor said. He added that none suffered from serious injuries.

Huseyin Capkin, Istanbul's police chief, confirmed the number of casualties, adding that one of the injured was a police officer who was passing by. He said the blast was caused by explosive material placed on an electric bicycle, creating a "medium-sized bomb".

Two public buses and a private vehicle were damaged by the blast, which also caused some damage to the windows of buildings in the immediate vicinity.

The site of the blast was cordoned off, and white-suited forensic teams combed the area for clues. Several police cars and ambulances were at the scene, and investigators said they had initially feared the possibility of a second blast.

No claim of responsibility

According to a resident of the area, the explosion took place towards the end of the morning rush hour, at around 9:00am local time (0600 GMT).

"We thought the building had collapsed. I even thought that a plane crashed into the next garden. Everybody was in panic," Ilhan Kurt, a pharmacist at a store nearby, told the Reuters news agency.

"It wasn't like gunfire. It was like an explosion," Tuncay Ozdemircan, a resident of the area, told Reuters.

"When I looked out of the window I saw yellow and white smoke rising, and I thought that it was a bomb," he said.

Etiler is a mainly residential and shopping distict in Turkey's largest city.

Turkey is due to vote in a parliamentary election on June 12. Security forces have been on alert amid fears of attacks by the Kurdistan Workers Party (PKK), a Kurdish separatist group.

Earlier this month, the group claimed responsibility for an attack on a police bus as it accompanied a campaign bus for Turkish prime minister Recep Tayyip Erdogan's Justice and Development Party (AKP).

There has been no immediate claim of responsibility for the blast.

"The aim of the attack is to prevent Turkey from discussing democracy, elections, a new constitution," said Suat Kilic, an AKP parliamentarian, following the blast.

"Terrorist organisations carry out these attacks before every election [...] The attack aims to prevent AKP from gaining enough seats to change the constitution," Kilic said.

"They will not get away with it,'' Police chief Capkin said of the culprits. "The people of Istanbul should feel at ease.''

Source: Agencies