UPDATE 1-S.Africa's MTN Q1 subscribers up 4 pct

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* Growth in Nigeria, South Africa, Iran (Adds details)

JOHANNESBURG, MAY 4 (Reuters) - MTN Group, Africa's largest mobile operator, reported on Friday a 4 percent rise in subscribers for the first quarter, helped by increases in its key markets of South Africa, Nigeria and Iran.

MTN, which is currently the target of a lawsuit from rival Turckcell, said in a statement its subscribers totalled 170.6 million at the end of March, from 164.5 million at the end of December.

The number of subscribers rose by around 3 percent in South Africa and Nigeria, while its customers in Iran increased by more than 6 percent.

Iran has been a significant money-spinner for MTN, although it has also brought serious controversy. Turkcell is suing MTN for at least $4.2 billion in a U.S. court, claiming MTN used corrupt practices and promises of weapons to win its licence in Iran.

Turkey's largest mobile operator initially won the bid for the Iran licence in 2004. Tehran later backed out of the deal and awarded the business to MTN in 2005.

MTN has said the case has no legal merit.

Shares of MTN were up 1.4 percent at 136.41 rand at 1146 GMT. (Reporting by David Dolan; Editing by Ed Cropley)

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