A protester has climbed on to the balcony of the Iranian embassy in central London and pulled down the country’s flag during an anti-regime demonstration.

Social media footage appeared to show a man replacing the flag with the pre-Islamic revolution lion and sun flag, often used by opposition groups in the country.

The Iranian embassy later posted a picture on its X account of the flag back in place with the caption “Iran’s flag is flying high”.

The Metropolitan police said an estimated 500 to 1,000 people attended the protest on Saturday at its peak in Kensington.

Iran’s lion and sun flag is often used by opposition groups in the country. Photograph: Dinendra Haria/LNP

Two arrests were made, one for aggravated trespass and assault on an emergency worker and one for aggravated trespass. Officers are also seeking another individual for trespass.

The force said: “We saw no serious disorder and officers will remain in the area to ensure the continued security of the embassy.”

People demonstrating against the regime have been gathering outside Iranian embassies across the world. In Berlin, hundreds of people were seen waving Iran’s former imperial flag and carrying pictures of exiled crown prince Reza Pahlavi as they marched through the German capital.

The demonstrations in Iran began on 28 December and have transformed into the most significant challenge to the regime for several years.

Hundreds of Iranian protesters take part in a demonstration outside the embassy in central London. Photograph: Dinendra Haria/LNP

Earlier this week, the prime minister, Keir Starmer, condemned the killing of protesters in the country and urged Tehran to “exercise restraint” amid a crackdown on demonstrations.

At least 62 people are reported to have been killed and 2,300 detained during weeks of protests initially sparked by anger over the country’s ailing economy.

Iran’s leaders have shut down access to the internet and international telephone calls in response to the protests.

A UK government spokesperson said: “We are deeply concerned by reports of violence against protesters in Iran who are exercising their legitimate right to peaceful protest and are monitoring the situation closely.”

Pahlavi, the exiled son of the former shah of Iran, called for protesters to take to the streets on Saturday and Sunday and seize control of their towns. Based in the US, Pahlavi, 65, asked people on social media to hoist the pre-1979 “lion and sun” flag, which was used during his father’s rule.

He said the Islamic Republic would be brought “to its knees”, adding: “Our goal is no longer merely to come into the streets; the goal is to prepare to seize city centres and hold them.”