The U.S. Federal Reserve must pre-emptively state it will not buy more Treasury bills in order to implement a cohesive exit strategy from the massive monetary bailouts it has provided, economic consultants Ian Bremmer and Nouriel Roubini wrote in an opinion column on the Wall Street Journal's website.

Bremmer and Roubini wrote that if the stimulus packages are withdrawn too soon, there is a risk of relapsing into deflation, while if left too late, the economy could succumb to stagflation.

They also said that U.S. banking regulators should adopt the reforms agreed upon by the G-20 nations, including setting up an insolvency regime for institutions deemed too big to fail.

Bremmer and Roubini said that major institutions should have much higher capital requirements, greater liquidity buffers, lower leverage and lower involvement in risky and illiquid investments if they are depository banks.

The workings of such institutions should be supervised internationally, they said.

Bremmer and Roubini also said the Federal Reserve needs to exercise greater authority to regulate the mortgage markets to ensure that asset and credit bubbles do not emerge.

(Reporting by Biswarup Gooptu in Bangalore; Editing by Kim Coghill)