Prominent Black Lives Matters activists and celebrities have written to Nigeria's president demanding justice over the treatment of people during protests against police brutality.

The group, which includes singer Alicia Keys and campaigner Greta Thunberg, urged President Muhammadu Buhari to free jailed protesters.

They also called for a "transparent investigation" into the alleged killing of protesters by armed forces.

"We cannot stay silent," they said.

Witnesses say they saw soldiers open fire on protesters at a toll gate in the wealthy Lagos suburb of Lekki on 20 October. It followed weeks of protests, which began against the now-disbanded, much-hated police unit, the Special Anti-Robbery Squad (Sars), but then morphed into greater calls for better governance.

"In the midst of a global pandemic, your people sought to bring peace and justice to their land, and they made Africa and its diaspora proud in doing so," the letter to President Buhari said.

"Yet their peaceful requests were met with state-sanctioned violence and suppression, as your administration meted out unwarranted force against its own unarmed citizens."

The letter was organised by #BlackLivesMatter movement co-founder Opal Tometi, and timed to coincide with International Human Rights Day.

Other signatories included actors Kerry Washington, Danny Glover and Mark Ruffalo, as well as writers Afua Hirsch, Reni Eddo-Lodge and Naomi Klein.

"As people who have supported the Black Lives Matter movement in the United States and throughout the diaspora, we cannot be silent when similar atrocities take place in African countries," the letter said.

"We demand respect for the Nigerian people, especially as they engage in their constitutional right to protest grave injustices."

For Black Lives Matter, highlighting injustices on the African continent is part of its wider mission to intervene in violence inflicted on black communities by the state.

Many of the signatories to the letter are members of the African diaspora, including Opal Tometi, whose parents are Nigerian. She told the BBC she has friends and family in Nigeria, so this feels personal. She believes the international community needs to continue to apply pressure on the Nigerian government to deliver justice for victims of brutality by the armed forces.

However despite the big name endorsements, it's unlikely the letter will lead to a change of tack from the Nigerian government.

In the immediate aftermath of the Lekki tollgate shooting, public figures, including former US presidential candidate Hillary Clinton and President-elect Joe Biden, called on the Nigerian government to hold those accountable responsible.

But the comments were brushed off by the authorities; and just this week President Buhari reiterated that any form of violent protest would not be tolerated.

On Monday there was a heavy police presence around the tollgate following calls for a second phase of protests to begin. It seems the authorities are determined to stop a repeat of the scenes of widespread street protests across Nigeria in October.

However stopping the #EndSARS social media campaign will not be so easy. Young Nigerians have seen how much influence they can yield - this letter is evidence of that.

Just last night at the Mobos, Afro pop singer Tiwa Savage referred to the Lekki tollgate shooting in her performance, singing "who gave the order?" Young Nigerians have vowed not to give up until the question is answered.