WASHINGTON (Bloomberg) — US taxpayers may be on the hook for as much as $23.7 trillion to bolster the economy and bail out financial companies, said Neil Barofsky, special inspector general for the Treasury's Troubled Asset Relief Programme.

The Treasury's $700 billion bank-investment programme represents a fraction of all federal support to resuscitate the US financial system, including $6.8 trillion in aid offered by the Federal Reserve, Barofsky said in a report released yesterday.

"TARP has evolved into a programme of unprecedented scope, scale and complexity," Barofsky said in testimony prepared for a hearing today before the House Committee on Oversight and Government Reform.

Costs include $2.3 trillion in programmes offered by the Federal Deposit Insurance Corp., $7.4 trillion in TARP and other aid from the Treasury and $7.2 trillion in federal money for Fannie Mae, Freddie Mac, credit unions, Veterans Affairs and other federal programmes, he said.

Barofsky offered criticism in a separate quarterly report of Treasury's implementation of TARP, saying the department has "repeatedly failed to adopt recommendations" needed to provide transparency and fulfill the administration's goal to implement TARP "with the highest degree of accountability".

As a result, taxpayers don't know how TARP recipients are using the money or the value of the investments, he said in the report.

The Treasury has spent $441 billion of TARP funds so far and has allocated $202.1 billion more for other spending.

In the nine months since Congress authorised TARP, Treasury has created 12 programmes involving funds that may reach almost $3 trillion, Barofsky said.