The document was published by ACI Russia, the national organisation of Russian financial market specialists.
The bank's media relations department did not respond to a Reuters request to confirm the authenticity of the document.
Two financial market sources confirmed to Reuters that the document had been sent to brokers by the central bank.
It said the measures were being taken by the regulator "in connection with the current crisis in the financial market and in order to ensure the protection of the rights and legitimate interests of investors in financial markets".
The central bank order is valid from 7:00 a.m. on Feb. 28 until the "cancellation of this order".
The document does not specify whether it applies to government securities. The order does not apply to applications submitted before 7 a.m. Monday.
The document was signed by central bank deputy chairman Philip Gabunia.