Umno is on guard against conspiracies involving local and foreign actors plotting to topple Prime Minister Najib Abdul Razak, Umno information chief Annuar Musa said.

Annuar said the party was aware of former prime minister Dr Mahathir Mohamad's "vendetta" against Najib and was vigilant over foreign powers entering the picture as part of the "grand design".

"Umno will be more careful in reviewing each issue it puts forward, more so when it involves foreign nations that have a record of interfering in the affairs of other countries, especially Muslim countries.

"(The interventions) eventually lead to war, political instability and destruction," he said in a statement.

"Umno and its leadership must be careful not to be trapped in Mahathir's grand design to seize power in Umno and the government, involving foreign powers.

"We believe Mahathir will use his trademark 'the ends justify the means' ways," Annuar said.

His statement comes after Umno Youth vice-chief Khairul Azwan Harun lodged a police report claiming top level conspiracy to oust Najib.

Khairul Azwan accused former attorney-general Abdul Gani Patail, former Bank Negara Malaysia governor Zeti Akhtar Aziz and outgoing Malaysian Anti-Corruption Comission chief Abu Kassim Mohamed of leaking confidential information to foreign agencies to topple Najib.

Gani rubbished the claim as a "publicity stunt", Zeti said she would seek legal counsel before responding while Abu Kassim said he would respond soon.

Khairul Azwan's police report comes days after the US Department of Justice filed lawsuits to seize US$1 billion in assets it believes were purchased using funds siphoned from 1MDB.

The DOJ's court filing also details how funds went into the bank account of an unnamed 'Malaysian Official 1'.

The transactions match those referred to by attorney-general Mohamed Apandi Ali when he cleared Najib of wrongdoing over the RM2.6 billion found in the prime minister's personal bank account.

Najib has called for those named in the lawsuits to clear their names and said the government was committed to good governance. His stepson Riza Aziz is named in the lawsuits.

Responding to the US action on 1MDB, Annuar urged all to "look at the big picture from all angles".

He also cited a Quranic verse reminding the faithful to steer away from ill assumptions and fault-finding.

"1MDB is a legal matter that should not be politicised. All quarters should be patient and allow due legal process. Attempts to pre-judge the matter before that helps no one," Annuar said.