Türkiye's central bank sent a letter to local lenders on Monday, warning them against conducting forex transactions with foreign banks during "off hours" and offering deposits with very high interest rates to avoid bond holding requirements.

The central bank has introduced rules in recent months to reduce the gap between the policy rate and lending rates and encourage loans to sectors including exports and production.

The latest rule mandates lenders with less than half of deposits in the lira in 2023 to hold an additional 7 percentage points of government bonds. Authorities have also sought to dissuade forex holdings.

The central bank said banks should not direct customers to hold funds from lira loans in demand deposits and they should also not allow lira loans to be deposited in accounts under a scheme that protects against forex depreciation, it said.

Such issues are "not supportive of establishing financial stability," the central bank said, adding that lenders should make the maximum effort to abide by regulations.

The central bank had already warned banks last week about conducting forex sale-purchase transactions overnight, saying it will take "necessary measures" if the issue continues.

In the past, if central bank requests on various issues have not been followed, it has taken measures such as requiring banks to hold government bonds.