Should 'was' be used instead of 'were'?

[Tan Elaine]

It seemed so close in 2008. That summer, Newsweek's one-time "Asian of the Year" emerged from a long period of humiliation and incarceration that had begun in 1998 when, after falling out with the country's long-term leader, Tun Dr Mahathir Mohamad, Anwar had been stripped of office on what were widely regarded as trumped up charges of corruption and sodomy. The news made global headlines: the great leader of the "reformasi" movement was not only down but jailed too.

Should 'was' be used instead of 'were'?

Thanks.

[SirGod]

*Not a teacher

Not, it shouldn't.

... Anwar had been stripped of office on what were widely regarded as trumped up charges of corruption and sodomy...

Passive voice, plural.

[Rover_KE]

SirGod is right.

The charges were . . .trumped up.

Rover

[BookAddict]

The law of proximity would require was. Let's make a substitution:
it was regarded as .....

and an immediate question could be:
What was regarded ... ?

[freezeframe]

The law of proximity would require was. Let's make a substitution:
it was regarded as .....

and an immediate question could be:
What was regarded ... ?

It's not a law. It's something that happens in speech.

But in written English, you still need to have correct subject-verb agreement.