LAGOS — Airtel Africa plans to invest $1.1 billion in expanding its networks across Africa, Chief Executive Sunil Kumar Taldar said in a television interview. He said capital spending has already risen from about $120 million to $390 million across 14 markets, that spending in Nigeria has doubled and that data use is growing by more than 50 per cent. He said diesel in Nigeria now costs about N1,800 per litre, up from about N900.