Mining investment continuing: Swan

(AAP)

(AAP)

Companies are still investing in the mining boom even though the federal government's mining tax is just days away from its introduction.

Treasurer Wayne Swan says companies are still investing in the mining boom despite the federal government's approaching minerals resource rent tax (MRRT) that starts on July 1.

Mr Swan said there is a half trillion dollar investment pipeline that is just getting bigger with BHP Billiton recently announcing an $US845 million ($A843.44 million) investment in the Illawarra and Rio Tinto making an additional $4.2 million in the Pilbara.

"No matter (that) all of the scare campaigns, all the talking down of the economy, none of it stacks up when you actually look at the facts," Mr Swan told parliament on Monday.

"Their scare campaign is torpedoed everyday by the facts," he said pointing at the opposition benches.

Shadow treasurer Joe Hockey questioned Prime Minister Julia Gillard over a UBS Research analysis that says value of shares is going to drop because of the MRRT and the carbon tax, hitting the returns of millions of Australian shareholders.

Ms Gillard accused Mr Hockey of coming into the parliament with the usual negativity of the opposition trying to talk down the Australian economy and shares.

"Some days the opposition says this (MRRT) is too big and it will break the industry, then other days they say it won't generate enough money," Ms Gillard said.

"The fact they make both of the criticisms tells you something that they are just casting around for any reason to try and attack the minerals resource rent tax."