Nguyen Thi Hong, Deputy Governor of the State Bank of Vietnam, said at a government press briefing on Monday that the CAR of Vietcombank, BIDV, Agribank, and Vietinbank are now close to the minimum rate allowed by government regulations and international norms of 9 percent.

Thus, if they are not allowed to increase their capital, they would have to curtail or even stop lending, she said.

CAR is the measurement of a bank’s capital as a percentage of its risk-weighted assets. Thus, to increase its CAR, a lender has to either increase its capital or reduce the denominator, assets, mostly made up of loans.

"This will be a disadvantage as investment in Vietnam is mostly dependent on bank credit," Hong said.

The four banks account for almost 48 percent of total credit for the primary market, the government said in a recent report to the National Assembly.

Vietcombank and BIDV increased their capital this year after years of waiting, but industry insiders said they need to increase it further.

Vietcombank increased its capital to VND37.1 trillion ($1.61 billion) in January by selling a 3 percent stake to foreign investors.

BIDV last month became the largest bank by charter capital, with VND40 trillion ($1.73 billion), after selling a 15 percent stake to South Korea's KEB Hana Bank.

Vietinbank, where the government ownership is at the minimum permitted level of 65 percent, has not seen an increase in capital of VND37.23 trillion ($1.62 billion) since 2014.

Agribank, which is wholly state-owned, has the lowest charter capital among the four of VND30.77 trillion ($1.33 billion).