Cabinet documents revealed on Tuesday that the Federal Government has been planning an advertising campaign for weeks to promote the new tax laws before it declared the controversial new mining super profits tax.

Corresponding letters between Treasurer Wayne and Special Minister of State Joe Ludwig show the Government will expect the tax to affect share prices and superannuation funds.

It was reiterated numerous times by Prime Minister Kevin Rudd the recent unpredictability of the share market was due to the instability in global markets.

The Government started running its tax ads this week and may continue until August.

Opposition Treasury spokesperson Joe Hockey told media today the timing of the Government coincides with the coming elections.

"It seems to be the case that the spin and sell of the Government is driving the policy outcome and it's clearly driving the election timetable."

Ian Macfarlane, the opposition resources spokesman, has accused the Government for leading them on the impact of the tax.

"It is clear the Government has been lying to the Australian people, and to the financial markets, and to the retirees, and to the superannuation funds," Mr. Macfarlane furiously said.

"It's gone in for a tax grab. It knew it would damage Australian companies. It knew it would damage the shareholdings of self-funded retirees and superannuation holders.”

However, Treasurer Wayne Swan said no apologies should be made by the Government regarding the ads.

"I think it's very important that the public has an accurate view of what the Government is planning," he told Radio National.

"We will not be deterred by this huge war chest of the mining industry."