President Trump has dismissed attempts to force him from office as a sham and a witch hunt.

But his impeachment trial in the US Senate has formally got under way.

And even as senators were making their final preparations to try him over claims he pressured a foreign government to investigate his political rival, there came a dramatic new twist.

An independent watchdog is accusing him of breaking the law over the very issue on which he is being judged.

And that came just hours after a former aide to his personal lawyer implicated the President directly in the plot.

From Washington Sky's US correspondent Amanda Walker reports.

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