Private equity firm Actis and South African Rand Merchant Bank have agreed to help finance a $100 million shopping mall in Nigeria, as investors see strong retail growth in the country.

Actis, which manages $4.8 billion in investments, said on Monday it will hold a 60 percent equity stake in the project in Nigeria's commercial hub Lagos. Rand Merchant Bank and local firm Paragon will each hold 20 percent.

The vast majority of Nigeria's 140 million people live on less than $2 a day but economists say the country has a burgeoning middle class that could help the OPEC member's economy overtake South Africa's in coming years.

"By providing world class retail and commercial space in the area, we hope to help revitalise the mainland of Lagos as we seek to grow our real estate portfolio across West Africa," said Actis West Africa managing director Ngozi Edozien.

The private equity firm also has investments in Tanzania, Ghana and Mauritius.

South Africa's Standard Bank and local Nigerian unit, Stanbic IBTC will provide debt of $48.6 million for the shopping mall.