Explosive new allegations to be made in the Dáil this week will claim that highly questionable share dealings made by AIB-owned Goodbody Stockbrokers and transacted through financial centres in the South Pacific and Caribbean went on for much longer than previously disclosed and were done using a huge range of shares.

Millions of euro in shares, including all classes of domestic and international stocks, were transacted from Dublin through the opaque offshore companies as a matter of routine for several years. Goodbody claims its legal advice has provided legal support for the transactions.

According to the new claims, the profits and losses on the share transactions were deliberately hidden through companies based in the formerly black-listed financial centres and involved dealings in scores of shares, not just AIB shares, as was suggested last week.

The so-called arrangements may have started as far back as the flotation of Irish Life on the Dublin and London stock markets in 1991. The arrangements are believed to have ended in 2001, meaning the share transactions could have taken place for over a decade.

TD Fergus O'Dowd , a senior member of the Oireachtas Committee on Economic Regulatory Affairs, has tabled parliamentary questions asking Taoiseach Brian Cowen and finance minister Brian Lenihan about the government's knowledge, if any, of the share transactions. He is also this weekend writing again to the Financial Regulator and the Irish Stock Exchange to request more information, in an attempt to learn when in the 1990s the practices first began and what other company shares, other than AIB's, were traded by its own broker.

The South Pacific and Caribbean centres, notorious at the time for their failure to sign up to international anti-money laundering accords, were referred to last week at a hearing of the Oireachtas regulatory committee by AIB's former group internal auditor, Eugene McErlean.

The regulator also said that "ultimately significant personnel changes took place in Goodbody" at the time. Sources say all the Goodbody dealings were detailed in AIB's unpublished internal report, called 'Special Investigation Goodbody Stockbrokers – Trading in AIB shares'. That report was sent to the Financial Regulator and the Irish Stock Exchange in 2001.

"It seems that the use of these offshore vehicles and companies and arrangements was much greater than has yet been disclosed," said O'Dowd. The purpose of the companies appeared to be to hide a huge level of share transactions, not just those in AIB, he said.

It is understood the investigation by regulators of the day focused on the period July 2000 to 2001. An AIB spokeswoman said on Friday that all matters were "fully reported by AIB to the relevant regulatory authorities at the time, fully investigated and fully addressed... We would not, therefore, make any further comment".