Donald Trump's campaign chairman resigns over revelations about Ukraine work

It comes in the wake of a campaign shake-up and revelations about Ukraine work.

Republican presidential candidate Donald Trump's campaign chairman Paul Manafort has resigned.

In a statement, Mr Trump said Mr Manafort offered his resignation on Friday morning.

Mr Trump praised Mr Manafort's work on the campaign and called him a "true professional".

Mr Manafort is stepping down in the wake of a campaign shake-up, as well as revelations about his work for a pro-Russian political party in Ukraine.

The Associated Press reported on Thursday that Mr Manafort's firm orchestrated a covert Washington lobbying operation on behalf of Ukraine's then-ruling political party.

Mr Manafort and his deputy, Rick Gates, never disclosed their work as foreign agents as required under federal law.

Earlier in the week, the campaign added two new top officials to the campaign in a move widely seen as a demotion for Mr Manafort.