The International Development Secretary has been criticised for holding undisclosed meetings in Israel without telling the Foreign Office.
Priti Patel is said to have met Yair Lapid, the leader of Israel's centrist Yesh Atid party, and visited organisations to discuss departmental business.
One meeting, while she was said to be on holiday in August, was held at the suggestion of Mark Regev, the Israeli ambassador to Britain.
According to the BBC, ministers have accused Ms Patel of conducting her own "freelance foreign policy" on Israel.
Ms Patel, who is a former vice-chair of Conservative Friends of Israel, was joined by Lord Polak, CFI’s honorary president.
Other ministers reportedly claimed the meetings were potentially in breach of the ministerial code of conduct which says "ministers must ensure that no conflict arises, or could reasonably be perceived to arise, between their public duties and their private interests, financial or otherwise".
The BBC said a senior Downing Street official said Ms Patel had done nothing wrong.
However one minister said: "This is outrageous. She is a Cabinet minister. She just cannot do this."
Another former minister said: "What does it say to the rest of the Middle East if a senior Cabinet minister in charge of Britain's huge aid budget disappears... from a family holiday in Israel and is under the wing of a pro-Israeli lobbyist?"
Lord Polak told the BBC he and Ms Patel were merely on holiday at the same time and had met for a catch up.
He said: “We met up for one or two things. It was the summer holidays. I just joined her for a couple of days, some drinks, some dinner, that kind of thing."
Lord Polak was accused of facilitating Ms Patel’s meeting with Mr Lapid.
"He is just an old friend of mine, a personal friend. He is more a journalist than a politician. We just had coffee with him. It wasn't anything formal. It is all very innocent," Lord Polak said.