China's biggest banks are seeking to loosen the regulatory requirement on provisions, as a slowing economy causes a surge in bad loans, transcripts of analyst calls following third-quarter earnings at two of China's Big Four banks show.

China's lenders are required to have a minimum loan loss provision ratio of 150 percent, a balance sheet calculation measuring the cash set aside for future losses by the total volume of non-performing loans (NPLs).

The requirement is "relatively high compared with international standards", an executive at Industrial and Commercial Bank of China Ltd, the country's biggest lender by assets, told analysts on its earnings call, according to a transcript of the call seen by Reuters.

ICBC said banks were in talks over provision requirements with the banking regulator, without giving further details. The bank would implement the decision of the regulator said.

China Construction Bank Corp, the country's second-biggest lender, also said in its earnings call that the bank was talking with regulators on the "high" provision requirement, according to separate transcripts.

As China's economic growth declines to its slowest pace in a quarter century, borrowers are finding it harder to repay borrowing, causing commercial bank NPLs to increase.

ICBC reported a NPL ratio at the end of September of 1.44 percent, up from 1.13 percent at the end of 2014, while its provision ratio declined to 157.63 percent, from 206.9 percent.

Bank of China reported a NPL ratio of 1.43 percent, and a provision ratio of 153.72 percent, compared with an NPL ratio of 1.18 percent and a loan loss provision ratio of 187.6 percent at the end of last year.

"The whole point for banks to put aside part of their earnings during strong economic years is so they can accumulate impairment allowances for the rainy days," said a Hong Kong-based analyst. "When the high NPL period really comes, they should have the flexibility to use the impairment allowances to deal with it."