Religious freedom advocacy CSW has expressed "deep concern" after a number of people were arrested by Eritrean security officers at a church gathering in the country's second largest city of Keren on Sunday.

The UK-based organisation said those arrested at the gathering of Faith Missions Church members included pregnant women, children and at least one entire family.

The arrests came just a week after Eritrean authorities seized 21 Catholic Church health facilities and arrested five Orthodox priests - all over a 24 hour period between 12th and 13th June. Daniela Kravetz, UN special rapporteur on the situation of human rights in Eritrea, said in a statement issued after the seizures that the actions "show that, despite the improved regional climate for peace and security, the human rights situation in Eritrea remains unchanged".

Mervyn Thomas, CSW's chief executive, said the organisation was "deeply concerned" at the latest arrests which he described as the "latest development in a crackdown on people of faith in Eritrea that has been ongoing since 2002".

That was the year, says CSW, that the government introduced a registration policy that effectively outlawed all religious practices not affiliated with the Catholic, Evangelical Lutheran or Orthodox Christian denominations and Sunni Islam, and began a campaign of arrests targeting unsanctioned denominations that continues to date, and that also affects the officially sanctioned religious communities.

Thomas called for the "immediate and unconditional release of all members of Faith Missions Church, as well as all other prisoners of conscience in the country".

"It is essential that UN member states seize the opportunity presented during next week’s interactive dialogue at the HRC to raise these concerns. We also urge member states to support and facilitate the renewal of the Special Rapporteur’s mandate in order to ensure continued monitoring of the dire human rights situation in Eritrea.”

Eritrea's human rights record will come under scrutiny when Kravetz speaks at the UN's Human Rights Council on 2nd July.