New York's banking regulator is pushing to install government monitors inside the US offices of Deutsche Bank and Barclays as part of an intensifying investigation into possible manipulation in the foreign-exchange market, according to people familiar with the probe.

The state's Department of Financial Services notified lawyers for the two European banks earlier this month that it wanted to install a monitor inside each firm, based on preliminary findings in the agency's six-month currencies-market probe, these people said. Negotiations are continuing over the details of the monitors' appointments, but New York investigators expect to reach an agreement soon.