Attorney-General George Brandis has been asked to make a statement explaining when he first became personally involved in the Bell Group litigation.

Four senators, Labor's Penny Wong, Greens leader Richard Di Natale and crossbenchers Derryn Hinch and Nick Xenophon, have written to the attorney seeking a statement be made on Tuesday, when he appears at a Senate estimates hearing.

In November last year, Senator Brandis made a statement to the Senate in which he said his first "personal involvement" in relation to the Bell Group litigation was on March 3, 2016.

He stood by the statement when asked about it at a Senate committee in December.

But last week the West Australian attorney-general Michael Mischin told the ABC's 730 program he had spoken to Senator Brandis about the issue in early February 2016.

The four senators in their letter to Senator Brandis, obtained by AAP, said the state attorney's comment was "clearly inconsistent" with the federal attorney's parliamentary statements.

"We invite you to take the opportunity at the beginning of this hearing (of the legal and constitutional affairs committee) to make a full statement explaining the inconsistency," the letter read.

"Should you not accept this invitation we will need to consider further options to ensure an appropriate explanation to the Senate."

Non-government senators have been seeking to clarify whether the attorney-general sought to favour the WA government over commonwealth taxpayers when it came to the liquidation of the failed Bell Group of companies operated by Alan Bond.

The WA government believed it had an agreement with Canberra, but was dudded when the Australian Taxation Office and the commonwealth successfully challenged WA laws relating to the Bell Group in the High Court.