Existing shareholders have until 18 September to take up the rights issue.
Zain says the extra capital will be used to finance its future expansion plans as well as meet its financial commitments.
The company has previously said it will bid for one of two mobile phone operators in Lebanon that are expected to be privatised in spring 2009.
Zain chief executive officer Saad al-Barrak has also said that he would buy stakes in state-owned operators in Algeria and Iran, if possible (MEED 14:9:07).
The governments in the two countries have said that they expect to sell stakes in Algerie Telecom and Telecommunications Company of Iran respectively before the end of 2008.