Australian politicians have been told they can view the current confidential negotiating text for the Trans-Pacific Partnership agreement, but only if they agree not to divulge anything they see for four years, despite expectations the deal could be finalised within months.

As 10 years of highly secret negotiations over the 12-nation trade and investment pact draw to a close and the US Congress debates whether to grant president Barack Obama fast-track authority, MPs and senators were briefed on the deal Monday night by the Department of Foreign Affairs and Trade assistant secretary Elizabeth Ward and other officials.

The MPs were told that, despite the negotiations being “in the final stages” and “at the end game”, key provisions had not been agreed – including intellectual property clauses of deep concern to the Australian government and controversial legal avenues for corporations to take action against governments – so-called investor state dispute settlements (ISDS). They were also told the ISDS process itself was still being negotiated, including provisions on transparency.

They were told they could view the current TPP negotiating text on Tuesday “subject to certain confidentiality requirements” and were shown a document they would be required to sign before any viewing.

The document listed requirements which it said were “consistent with the undertaking by Australia and other negotiating partners to treat negotiating texts and other documents exchanged in the course of negotiations as confidential government information in order to facilitate candid and productive negotiations”.

The requirements listed were as follows:

“I will not divulge any of the text or information obtained in the briefing to any party, I will not copy, transcribe or remove the negotiating text” and “I further acknowledge that the negotiating text is confidential and sensitive; disclosure of the negotiating text may affect adversely TPP negotiations and Australia’s relations with other TPP partners.”

It concluded: “I therefore agree that these confidentiality requirements shall apply for four years after entry into force of the TPP, or if no agreement enters into force, for four years after the last round of negotiations.”

Among those attending the briefing were Coalition backbenchers Bruce Scott and George Christensen, Labor backbenchers Stephen Jones, Andrew Giles, Melissa Parke and Terri Butler and independent senator Nick Xenophon.

The four-year confidentiality provision mirrors the secrecy provisions printed on the investment chapter of the TPP, which was published by Wikileaks in March.

That document said it could be declassified “four years from entry into force of the TPP agreement or, if no agreement enters into force, four years from the close of the negotiations” and said it “must be protected from unauthorized disclosure ... and must be stored in a locked or secured building, room, or container”.

When Christensen queried the four-year timeframe at the meeting he was told it was needed because the final version of the document might be different from the current version, and that it was similar to the undertakings required of members of the US Congress who wanted to view the text.

Among the most controversial provisions of the TPP is the proposed investor state dispute settlement mechanism, which could allow multinational corporations to challenge Australian government policies in international arbitration tribunals, for example plain-packaging laws or environmental or health regulations.

The former Labor government put a footnote into the TPP investment text saying Australia did not agree to ISDS provisions. The current government has – according to the leaked Wikileaks version – added that it is prepared to agree to ISDS if “certain conditions” are met.

Australia wants exemptions from intellectual property provisions for “any measures comprising or related to the Pharmaceutical Benefits Scheme, Medicare Benefits Scheme, the Therapeutic Goods Administration and the Office of the Gene Technology Regulator”. The government is particularly concerned to make sure the agreement does not require Australia to extend the period that drugs remain on patent, because of the huge potential impact on the cost of Australia’s pharmaceutical benefits scheme.

Parke said she still had “extremely grave concerns about the ISDS provisions. I note that the briefing confirmed that the Philip Morris scenario could still happen under this agreement”.

The tobacco giant is using ISDS provisions in Australia’s free-trade agreement with Hong Kong to challenge plain-packaging laws that have been upheld by Australia’s high court.

Xenophon said he was also concerned about ISDS, saying “40 years ago Gough Whitlam abolished appeals to the [British] privy council in what was a watershed moment for Australian sovereignty. We now seem to be going back to the colonial era where court cases, not just appeals, will be determined overseas”.

Butler said she also “remained concerned about the ISDS provisions ... I will need a lot more information to be satisfied this is in the national interest, compared with the status quo, which is the bilateral trade agreements we already have with most of these countries”.

After the Wikileaks revelations, the trade minister, Andrew Robb, insisted “the government will not support outcomes that would increase the prices of medicines for Australians or adversely affect our health system more generally; end of story ... Nor would we accept outcomes that undermine our ability to regulate or legislate in the public interest in areas such as health”.

In recent interviews and opinion pieces, Robb has said the deal could provide huge benefits for Australian exporters – including agricultural exports – and says ISDS provisions have been included in many bilateral agreements Australia has already signed. The only time they have been used against Australia is the ongoing case being brought by Philip Morris but Australian companies have successfully used the clauses against companies in India.

He says the government has conducted more than 1000 consultations with different groups about the TPP talks.

“It’s not secretive but of course the whole text is not available because nothing’s agreed until everything’s agreed, so to be putting out bits and pieces over five years, which may or may not end up in the final document, all that’s going to do is be a source of material for those anti-trade groups to worry people and misrepresent, he told the ABC.

The TPP is being negotiated with the US, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore and Vietnam.

The cabinet will decide whether Australia signs any final agreement, and then text will be tabled in parliament and be considered by the Joint Standing Committee on Treaties before implementing legislation is considered by the House of Representatives and the Senate.