Zambia’s finance minister urged South African firms to invest in roads and power plants in Africa’s No.2 copper producer after it suspended borrowing indefinitely, slowing down the accumulation of new debt amid worries about the risk of distress. The International Monetary Fund rejected Zambia’s borrowing plans in February, saying its debt load was harder to sustain. Freezing new debt could clear the way for Zambia to agree a $1.3-billion loan agreement with the IMF.