A man exploded a small, homemade device outside the United States Embassy in Beijing yesterday that injured only himself, the authorities said.

The explosion occurred at 1pm, with photos on social media showing smoke and commotion at the scene following the blast. Police cordons were put up as dozens of uniformed officers swarmed the scene.

The Beijing Police Department issued a statement that identified the suspect as a 26-year-old man surnamed Jiang from Tongliao City, Inner Mongolia.

It said that at 1pm yesterday, a man ignited a suspected firecracker-like device at the intersection of Tianze Road and Anjialou Road in the city's Chaoyang district, resulting in injury to his hand that was not life-threatening.

A nearby patrol car was quickly dispatched to the scene, where the suspect was taken into custody and sent to hospital, it added. No others were hurt in the incident.

A US Embassy spokesman confirmed that no other people were injured and that there was no damage to embassy property, but called the device a bomb.

"There was an explosion at approximately 1pm on the street outside the south-east corner of the embassy compound," she said.

"According to the embassy's regional security officer, there was one individual who detonated a bomb."

Neither the police nor the embassy commented on a report by The Global Times that officers had earlier removed from outside the embassy a woman who had sprayed petrol on herself in a "suspected attempt at self-immolation" around 11am.

Asked about the incident at yesterday's regular press briefing, Chinese Foreign Ministry spokesman Geng Shuang called the blast "an isolated public security incident", adding that the Chinese police handled it in a timely and proper manner.

The blast immediately trended on Chinese social media, with hashtags such as "US embassy blast" exceeding six million hits. But censors swung into action and soon removed such posts en masse from platforms such as Weibo.

There was no official word on possible motives for the blast. It comes amid a trade dispute between the US and China, with both sides imposing tit-for-tat tariffs on billions of dollars worth of goods.

Besides the US Embassy, the upmarket neighbourhood in north-east Beijing where the blast occurred is also home to the embassies of India, France, Malaysia and Japan, and a Chinese Ministry of Foreign Affairs compound. Police said investigations were ongoing.