Before the announcement of the National Broadband Network is made, Telstra says it will assist with a query by the corporate watchdog into movements in its share price.

An insider trading may have been behind a flow in the Company's share price before the deal was announced, according to speculations.

Pronouncing it as the busiest day More than $198 million worth of Telstra shares were traded on Friday. The Company's share price closed seven cents higher, compared with the preceding day.

After the matter was raised by opposition treasury spokesman, Joe Hockey, the Australian Securities and Investments Commission are expected to investigate the movement. The Company would cooperate with any ASIC probe, a spokesman for Telstra said.

Mr. Hockey raised the issue on Monday night with Corporate Law Minister Chris Bowen, who in turn referred the matter to ASIC.

Mr. Bowen said, "I have not looked at the Telstra share price movements over recent days. I make this point: the government takes these matters very seriously".

He said he was very concerned about the proposal that there may have been unlawful trading in Telstra shares ahead of the NBN announcement.

Telstra has signed a pact to rent some of its infrastructure to NBN Co., the Company that will construct and run the NBN.

This deal, which will make the rollout of the NBN quicker and cheaper, ended more than 12 months of negotiations between Telstra and the Government.