She added later: "Even by this Administration's abysmally low standards, Secretary Pompeo's decision to serve as an errand boy for the President's re-election on a taxpayer-funded diplomatic mission, and his decision to use one of our closest partners as a political prop in the process, is absolutely disgraceful."
The Trump Administration has been a strong supporter of the Israeli Government, and the US President has touted his decision to move the US embassy to Jerusalem and plans for Middle East peace as successes.
No sitting secretary of state has made a speech at a modern day party convention, according to the Washington Post, though some have attended the gatherings.
Traditionally people in the post have long expressed the importance of a separation between their role heading up the US diplomatic services and involvement in party politics.
Furthermore, only last week US diplomats were explicitly warned from participating in "partisan political behaviour while posted... abroad, even on personal time", a rule Pompeo is accused of breaching.
The State Department said Pompeo was making his remarks in a personal capacity and that no department resources would be involved.
The clash was the most eye-catching element of a wider row about whether Trump was blurring the line between governmental work and political campaigning as he used the White House as the backdrop for the four-day Republican Convention.
Yesterday Trump appeared in two videos where he chatted to groups of Americans - first frontline workers impacted by the coronavirus pandemic, then US hostages released during his presidency - from inside the White House.
The videos appeared to be an attempt to play up Trump's empathetic side after Biden's humanity featured heavily as a theme in the Democratic Convention last week.
"You represent an incredible group of people and we love you all," Trump told the group, which included nurses, postal workers and recovered coronavirus patients.
Melania Trump, the first lady and Trump's third wife, was scheduled to speak from the White House's Rose Garden and Trump will give his closing convention speech address from the White House on Friday.
The President's son, Donald Trump jnr, was among a string of convention speakers yesterday to cast Biden and the Democrats as politicians pushing a "socialist" agenda who endangered American values.
"Biden has promised to take that money back out of your pocket and keep it in the swamp," Trump said, referring to the Democrats' promise to reverse his father's major tax cut.
