President Donald Trump’s personal lawyer Rudy Giuliani insists he will not comply with a subpoena issued by US House of Representatives Democrats seeking documents as part of their impeachment inquiry.

A letter from a lawyer representing Mr Giuliani dismissed the inquiry, calling it ‘‘unconstitutional, baseless and illegitimate’’, and claimed the information sought relating to his work in Ukraine is protected by attorney-client privilege and executive privilege.

Rudy Giuliani’s lawyer has sent a letter to Congress saying he doesn’t intend to comply with a congressional subpoena for documents. Here’s the letter: https://t.co/QXln8b9phS pic.twitter.com/Bwb6jkLWox

— Rebecca Ballhaus (@rebeccaballhaus) October 15, 2019

The move represents the latest effort by Mr Trump and those close to him to refuse any cooperation with the inquiry.

“In addition, the subpoena is overbroad, unduly burdensome, and seeks documents beyond the scope of legitimate inquiry,” Jon Sale, the lawyer for Mr Giuliani, wrote.

Attorney-client privilege is a legal principle in which certain confidential communications between a lawyer and client are kept secret. Executive privilege is a legal doctrine under which a president can keep certain information from other branches of government.

The House Intelligence Committee had demanded that Giuliani hand over by Tuesday documents related to Trump’s effort to pressure Ukrainian President Volodymyr Zelenskiy to investigate Joe Biden, potentially Trump’s opponent in the 2020 election.

Tuesday’s letter from Mr Sale could prompt House Democrats to file a lawsuit intended to force Mr Giuliani to comply with the subpoena.

Mr Sale said Mr Giuliani was adopting arguments made by Pat Cipollone, the top White House lawyer, in an October 8 letter to House Speaker Nancy Pelosi, the top Democrat in Congress.

In that letter, Mr Cipollone said the House impeachment inquiry was constitutionally invalid and denied Trump basic due process rights, such as the ability to cross-examine witnesses, call witnesses to testify, receive transcripts of testimony, and have access to evidence.

Many legal experts have rejected Mr Cipollone and Mr Giuliani’s arguments that the impeachment investigation is unconstitutional.

-with AAP