Christian Solidarity Worldwide (CSW), will join Human Rights Concern Eritrea, Release Eritrea, the Medhanie Alem Eritrean Orthodox Church and the British Orthodox Church to protest the continuing repression of freedom of religion or belief in Eritrea.
CSW said the names of 25 Christians who are confirmed to have died at the hands of the regime since 2005, either in prison or soon after incarceration, will be read out by campaigners.
The event will mark the 15th anniversary of severe restrictions on Eritrea's Christian community and the closure of churches affiliated to targeted denominations.
In March 2002, the government outlawed all practices not affiliated with the Catholic, Evangelical Lutheran or Orthodox Christian denominations and Sunni Islam, and began a campaign of arrests targeting unsanctioned denominations.
CSW claimed the Eritrean regime is responsible for 5000 Eritreans fleeing the country every month.
The charity said: "On 17 March 2017, two Pentecostal Christians reportedly died in hospital after undergoing a hunger strike to protest the abuse they suffered in prison."
The United Nations Commission of Inquiry on human rights in Eritrea (COIE) report in 2016 found "reasonable grounds to believe" that crimes against humanity have been committed by state officials in a "widespread and systematic manner" since 1991.