Who are the 9 witnesses scheduled to testify this week in the Trump impeachment inquiry?

WASHINGTON (REUTERS) - The US House of Representatives' impeachment inquiry of President Donald Trump shifts into higher gear this week when a parade of officials will face questioning by lawmakers over Mr Trump's dealings with Ukraine.

The following are the nine witnesses scheduled to testify in what is the second week of the televised hearings.

- Jennifer Williams, an aide to US Vice President Mike Pence

- Alexander Vindman, Director for European Affairs at the National Security Council

- Kurt Volker, US special envoy to Ukraine

- Tim Morrison, a former White House aide with the National Security Council who focused on Europe and Russia policy

- Gordon Sondland, US Ambassador to the European Union

- Laura Cooper, Deputy Assistant Secretary of Defence for Russian, Ukrainian and Eurasian Affairs

- David Hale, Undersecretary of State for Political Affairs

- Fiona Hill, former National Security Council senior director for Europe and Russia

- David Holmes, political counsellor at the US Embassy, Kiev, Ukraine