(Sharecast News) - Airtel Africa slumped on Friday as it posted a decline in first-half profit and revenues.

In the half year to 30 September, revenue fell 9.7% $2.37bn, hit in particular by "significant" currency devaluations in Nigeria, Malawi, Zambia and Tanzania.

Meanwhile, operating profit was down 20.3% to $706m.

Constant currency earnings before interest, tax, depreciation and amortisation rose 13.5% but reported currency EBITDA fell 16.5% to $1.08bn.

Airtel said EBITDA margins declined to 45.8% from 49.6%. This was put down mainly to the lower contribution of Nigeria following the depreciation of the naira and a significant increase in fuel prices.

The total customer base grew 6.1% to 156.6m. Airtel said data customer penetration continues to rise, driving a 10.4% increase in data customers to 66m. Data usage per customer was up 30.9% to 6.6 GBs, with smartphone penetration increasing 5.3% to 42.9%.

At 0920 BST, the shares were down 6% at 108.20p.