The deaths of dozens of people, including 67 South Africans, in a building collapse in Nigeria was shocking, Cosatu said on Wednesday.

The Congress of SA Trade Unions sent its condolences to all those who had lost loved ones in the collapse, spokesman Patrick Craven said in a statement.

The union federation sent its best wishes to the unknown number of people injured in the collapse, and wished them a speedy recovery.

Cosatu reiterated President Jacob Zuma's statement on Tuesday, when he said: "Not in the recent history of our country have we had this large number of our people die in one incident outside the country.

"The whole nation shares the pain of the mothers, fathers, daughters and sons who have lost their loved ones. We are all in grief."

Craven said everything possible had to be done to investigate the cause of the "catastrophe", and take steps to prevent any such accident from happening again in future.

"Meanwhile we hope that arrangements will be made to enable... family members to be flown to Nigeria to identify their loved one's bodies and that the remains of the deceased will be brought back home to South Africa as soon as possible."

A multi-storey guest house at the Synagogue Church of All Nations in Lagos, Nigeria, collapsed on Friday.

The South Africans killed were believed to be part of five South African tour groups lodging at the church of faith healer, "prophet" TB Joshua.

News agencies reported that over 100 survivors had been rescued.