"This major investment from AustralianSuper will promote growth and strengthen the UK's position as a leading financial centre, creating wealth and helping to fund public services," finance minister Jeremy Hunt said in the statement.

The announcement comes ahead of a budget update on Wednesday that Hunt is hoping will boost Conservative Prime Minister Rishi Sunak's flagging fortunes before an election later this year.

Last July, Hunt set out the Mansion House Compact, whereby 10 pension funds, including Aegon, Legal & General and Aviva, voluntarily committed to investing at least 5%, or about 50 billion pounds, in life science, fintech, biotech, clean tech and other types of high growth unlisted British companies by 2030.

"The raft of investment announcements we have seen today show that the UK remains one of the most attractive places to invest in the world," Sunak said in the statement.

"But because of the difficult, long term decisions the government has taken the economy is now turning a corner, and we must stick to the plan."

AustralianSuper, which holds more than 2.5 billion pounds in British-listed equities according to the statement, says on its website that it manages more than A$315 billion ($205 billion) of retirement savings on behalf of more than 3.3 million members.

Private markets overseas, especially debt, are top priorities for Australia's largest pension funds as they look for ways to deploy the rapidly growing A$2.4 trillion pool of retirement savings that is outgrowing the domestic market.

($1 = 0.7879 pounds)

(Reporting by Muvija M, editing by William James and Alex Richardson)