MANILA- The Marcos family cannot legally strike a deal with the government to return their ill-gotten wealth, a former government official said.

Former Presidential Commission on Good Government (PCGG) chief Ruben Carranza argued that accepting the Marcos family's offer to return gold bars and a portion of their hidden wealth can only proceed in an "unlawful" manner.

"It can’t be done lawfully because you already have several obstacles to carrying this out," Carranza said in an interview with ANC on Thursday.

President Rodrigo Duterte said Tuesday the Marcos family was willing to return gold bars and a part of their alleged hidden wealth, citing an emissary who said the riches were taken only to secure the Philippine economy at the time.

Carranza explained that returning the Marcoses' hidden wealth cannot be a subject of a compromise due to a 2003 Supreme Court ruling that declared assets of the Marcoses beyond $304,000 as ill-gotten.

"The sum of $304,372.43 should be held as the only known lawful income of respondents since they did not file any Statement of Assets and Liabilities (SAL), as required by law, from which their net worth could be determined," the High Court said in a July 2003 decision.

Formed nearly 30 years ago to recover an estimated $10 billion looted by the late dictator Ferdinand Marcos, the PCGG has already recovered $3.4 billion in ill-gotten wealth as well as jewelry, art, and other assets from the Marcoses.

Caranza said another obstacle to the supposed compromise is the Human Rights Victims Reparation and Recognition Act of 2013, which recognizes and provides monetary remuneration for victims of martial law.

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"This proposed agreement will in effect go around in question and therefore undermine the efforts of the state since 1986 to go after the Marcos family for accountability for the crimes they have committed," he said.

Carranza however explained that government efforts to go after the ill-gotten wealth of the Marcoses has no expiration period.

"All the periods of prescription to go after the ill-gotten wealth won’t apply because the Philippine constitution precisely says that there is no deadline to go after ill-gotten wealth," he said.

"This is not just about money. This is about justice and accountability and ultimately, this is about the truth," he added.