Governments in the United Arab Emirates, Qatar and Saudi Arabia have set up new Islamic banks to company with Islamic law, or Sharia, to ensure they retain an ethical image, the credit rating agency said.
The $700 billion (Dh2.6trn) Islamic finance industry has the potential to surge to as much as $4 trillion, it said.
"It is as if governments do not want to see the Islamic banking industry over-dominated by the private sector, in order to keep the whole thing under control," the ratings agency said in a research report on Tuesday.
"If governments have an increasing share of ownership in IFIs, the risk of consumers perceiving an IFI as insufficiently compliant with sharia is somewhat mitigated," it said.
Growth of Islamic financial institutions (IFIs) has been supported as a more than five-fold rise in oil prices since 2002 drives demand for products, including Islamic bonds and loans to finance major infrastructure projects, Moody's said.
Last year, Dubai opened Noor Islamic Bank with the aim of creating the world's largest Islamic bank within five years.
UAE capital Abu Dhabi this year started Al Hilal bank with Dh1 billion of capital, while Ajman set up Ajman Bank to tap growing demand for Islamic retail products.
Noor said last month it would set up a bank in the Maldives as part of a global expansion plan.
"Many new IFIs have clearly made their ambitions public; with very large capital bases right from inception, their vocation is immediately international," Moody's said.
"The larger newcomers have that ambition, beyond the natural borders of their respective domestic markets, into new territories where Islamic finance is not yet entrenched."