"Privatization will not become a conditionality for loans," said a source familiar with internal AIIB discussions, but who declined to be named because he is not authorized to speak publicly on the matter.
"Deregulation is also not likely to be a condition," he added. "The AIIB will follow the local conditions of each country. It will not force others to do this and do that from the outside."
The AIIB was not available to comment for this article.
A reduced focus on the free market could give the AIIB greater freedom to run projects, said a banker at a development bank who declined to be named.
Read MoreWhy the US shouldn't worry about the AIIB
For example, development banks that finance a water treatment plant may require the price of treated water to be raised to recoup costs, even if local conditions are not conducive to higher prices.
The AIIB, on the other hand, could avoid hiking prices and rely instead on other sources of financing, such as government subsidies, to defray costs, he said.
The bank, to which some 50 countries have signed up to join, also aims to have a simpler internal review and risk assessment system for projects compared with its peers to hold down costs and cut red tape, sources said.
For one, the AIIB is not expected to delay some project approvals by months to allow all parties to do due diligence, a practice in place at other development banks, said a source familiar with the matter.
The bank will also minimize expenditure by having only a handful of field offices and a staff strength of between 500 and 600, about a sixth of the size of the Asian Development Bank (ADB) and 5 percent of the World Bank, he said.
A successful AIIB that sets itself apart from the World Bank would be a diplomatic triumph for China, which opposes a global financial order it says is dominated by the United States and under-represented by developing nations.
Criticism of international development lending is not new, said Susan Engel, a professor at Australia's University of Wollongong who has studied the impact on the World Bank of free market ideas often referred to as the Washington Consensus.
"It's a religion - this commitment to the involvement of the private sector even in sectors where, in fact, their involvement is shown to do harm," Engel said of the U.S.-based lender.
In its infancy, two sources said the AIIB, with authorized capital of $100 billion, would concentrate on securing its credit rating, implying a more cautious approach.
This means it will run like an investment bank, funding only commercially sound projects, working on public-private partnerships where feasible, and charging market interest rates that are likely to be higher than those charged by its peers.
Read MoreIn China's 'fixed' market, rule breakers are probed
"Jin has pitched it as a bank that needs to at least break even," a source familiar with internal AIIB discussions said in reference to Jin Liqun, a former Chinese deputy finance minister and AIIB's first president.
But down the road, the AIIB could offer concessionary loans and go beyond building ports and funding water, energy and transportation deals to financing policy projects such as health and education, three sources said.
It may also expand its remit to fund projects in Africa, where countries have lobbied the lender to work in their region, a source said.
To meet its year-end deadline of starting operations, the AIIB has hired a team of former ADB and World Bank bankers, and is drafting its operations manual by revising the ADB and World Bank versions, three sources say.
Although the ADB and the World Bank downplay any rivalry between them and the AIIB, bankers say the AIIB's advent has prompted the two banks to review how they work, to the benefit of borrowers.
"The World Bank and the other development banks have become more risk-averse over time," said David Dollar, a former director of World Bank China who has advised Beijing on the AIIB. "That tends to be make them slow and bureaucratic."