Moody's downgraded Namibia's long-term issuer and senior unsecured ratings to Ba2 as public debt piles on, while growth remains weak for longer than anticipated.

The country's debt burden has more than doubled over the last decade — rising to 45.6% of GDP at the end of 2018 from 19.2% of GDP 10 years ago — and continues to increase despite spending constraints, Moody's said.

Based on previous "fiscal slippages," the rating agency expects the Namibian government to reach a primary budget surplus by 2023-2024 instead of the government's plans to reach it by 2021-2022. Meanwhile, public debt is projected to stabilize at just below 55% of GDP by 2024-2025, according to Moody's, compared with the government's expectations of debt stabilizing around 53% of GDP by 2022-2023.

The rating agency also expects weak medium-term economic growth prospects to add to Namibia's public debt burden, as it may constrain government revenue.

Negative spillovers from weak growth in South Africa are also likely to weigh on Namibia's economy as it depends on its neighbor's nonmineral exports, Moody's said. Limited investment in the mining sector is also projected to constrain Namibia's growth.

The outlook on Namibia's rating is stable.