MANILA - The widow of the late Philippine dictator Ferdinand Marcos has been sentenced to at least 42 years' jail over graft charges involving some US$658 million (S$905 million) that her family was accused of hiding through foundations set up in Switzerland.

An anti-graft court, referred to here as the Sandiganbayan, found former first lady Imelda Marcos guilty of seven counts of graft on Friday (Nov 9).

It sentenced her to six to 11 years' jail for each count.

The court also disqualified her from seeking public office.

The 89-year-old is running for governor of the northern province of Ilocos Norte, her family's stronghold.

She was allowed to post bail. Marcos said in a statement she issued later in the day that she would file an appeal.

Marcos is best known for leaving behind more than 1,200 pairs of shoes when her family fled the Philippines following an army-backed uprising in 1986.

Her husband, who was president for nearly two decades, was accused of amassing more than US$10 billion while in office and died in exile in 1989.

President Rodrigo Duterte's spokesman Salvador Panelo said the decision proved "the executive branch is not in the business of exerting undue interference or influence in the affairs of another separate and independent branch of the government".

The Marcos family is a close ally of Mr Duterte, a self-professed fan of Mr Marcos and his strongman ways.

He has said graft and illicit drugs were so entrenched in the Philippines that if he were not around, it would be better off run by a dictator like Mr Marcos.

Marcos' daughter, Imee, is running for a seat in the Senate with backing from a political coalition formed by Mr Duterte's daughter.

The graft cases, filed in 1991, stemmed from allegations that she had financial stakes in at least seven foundations set up in Switzerland while she was a government minister and governor of metropolitan Manila from 1978 to 1986, and a Member of Parliament from 1978 to 1984.

Government prosecutors said her involvement with these foundations while serving in government broke the law.

A government agency created to recover money purportedly stolen by the Marcoses had identified at least US$658 million stashed away in Switzerland via foundations set up by the family's lawyers and financial advisers.

One foundation, Avertina, had over US$240 million in its accounts.

Avertina resulted from the consolidation of two other foundations, one of which bore accounts with Credit Suisse under the names "William Saunders" and "Jane Ryan", which were later traced to the former first lady and her husband.

Two other foundations - Aguamina and Banque Paribas - held accounts worth around US$100 million.

Marcos supposedly took part in managing these foundations and four others.

She was also said to have taken part in running a Philippine company, Asian Reliability, that, through her intercession, received government loans.

Her lawyers had argued that "mere participation" in the Swiss foundations did not violate the country's anti-corruption laws because it did not involve any government transaction.

"There is no evidence that the accused indeed intervened in any matter before a government office for her pecuniary benefit," they said in a court filing.

They also claimed that "a foundation is not a business".

The foundations were not shown to be "engaged in commercial activity or for gain or livelihood", they argued.

The Commission on Human Rights called Marcos' conviction "a triumph for the Filipino people".

Its spokesman Jacqueline de Guia said there was "the need for truth, so that we can ultimately hold the dictatorship and their cohorts accountable for their crimes".

Representative Carlos Zarate, of the left-leaning Bayan Muna (People First) party, said the decision "puts to rest the Marcos family's contention that they have not amassed ill-gotten wealth nor plundered the country's coffers during their reign".