A number of moderate and left-wing political groups in Iran say they've formed a coalition to fight their conservative rivals in next month's municipal elections.

The alliance of sixteen groups will include the influential League of Militant Clerics and Iran's largest student movement A similar coalition helped the moderate politician, Mohammad Khatami, secure victory in last year's presidential contest.

A BBC Iranian affairs analyst says the municipal elections -- the first nationwide polls since the Islamic Revolution in 1979 -- are being seen as an important test in the power struggle between President Khatami and powerful conservative factions.