Econet disputes Zain's ownership of Zain Nigeria

* Econet wants Zain Nigerian acquisition unwound

* Row could stop Zain's plans to divest stake or African ops

* Zain denies undertaking to preserve status quo JOHANNESBURG/LONDON, Oct 7 (Reuters) - South Africa-based Econet Wireless is disputing Gulf carrier Zain's (ZAIN.KW: Quote) ownership of one of its most important operations, Zain Nigeria, in a row that could derail Zain's divestment plans.

Econet said on Wednesday it disputed the purchase in 2006 by Celtel, now called Zain, of a majority stake in a group called Vee Networks Limited, now Zain Nigeria.

Econet -- which has operations in nine countries in Africa, Europe and the East Asia Pacific Rim -- said in a statement it was pursuing arbitration proceedings because it believed it had been denied its right of first refusal over the stake.

It has now appealed to legal authorities including an international tribunal operating under the auspices of the United Nations for the transaction to be unwound.

The South African group was a founding shareholder of Vee Networks and claimed that its right of first refusal over the stake was breached in 2006, when its Nigerian partners sold their shares to Zain.

Econet said the arbitration would result in Zain's being unable to dispose of its Nigerian operation until the issue is resolved, if it decides to sell its African operations.

Zain, a hot but tricky potential acquisition target for stagnating Western telecoms groups, has invested more than $12 billion in Africa. Nigeria is the group's biggest market, contributing 21 percent of customers and 17 percent of revenues.