Russia could have become an “associate member” of Nato 25 years ago if a Ministry of Defence proposal had gained support, according to confidential Downing Street files which also expose Boris Yeltsin’s drinking habits.

The suggestion, aimed at reversing a century of east-west antagonism, is revealed in documents released on Tuesday by the National Archives at Kew.

Presented by Malcolm Rifkind, then defence secretary, to a Chequers strategy summit, the plan was to dispel Kremlin suspicions of the alliance’s eastwards expansion.

In 1995, Yeltsin was president and the cold war over. Relations were in flux as a Russia tried to come to terms with shrunken international borders.

Yeltsin was proving an unpredictable ally. Files show that he urged western leaders at a summit in Halifax, Canada to delay Nato enlargement until after Russia’s elections because “public discussion could provoke trouble”.

But poor health and heavy drinking jeopardised his authority. The previous year he had notoriously failed to disembark from a plane during a stopover in Ireland amid rumours of alcoholism and a heart attack.

In July 1995, the Moscow embassy cabled about Yeltsin going into hospital due to his “longstanding heart condition”. At Hyde Park, the Roosevelt home in New York, according to US diplomats, Yeltsin subsequently appeared “rolling, puffy and red”.

He consumed “wine and beer greedily … and regretted the absence of cognac. One of his aides took a glass of champagne from him when the aide felt enough was enough and he was alcoholically cheerful at his press conference with Clinton.”

Facebook Twitter Pinterest Sir Malcolm Rifkind: ‘I was trying to find a way to say could we support close cooperation with Russia.’ Photograph: David Levene/The Guardian

The Foreign Office drafted a note headed: “Contingency Planning for Yeltsin’s Death”. It stated: “Yeltsin is six years older than the average life expectancy of the Russian male (58) and has now had two heart attacks in three and a half months.

“His approved intention to curb his drinking after his first heart attack did not endure; there is little reason to be confident that he will do better this time. He is a bad insurance risk.” A message of condolence from the prime minister was prepared in case of sudden death.

The idea of soothing Russia’s anxieties emerged in preparatory notes for the foreign policy seminar at Chequers.

In a 10-page submission, Rifkind argued that: “A possible solution would be to create a new category of associate member of Nato. Such a status could not involve article V guarantees [which declares an attack on one state is an attack on all members], membership of the IMS [Nato’s International Military Staff ] or Russian vetoes and would not therefore change the essence of Nato.

“It would, however, give Russia a formal status within Nato, allow it to attend, as of right, ministerial and other meetings and encourage a gradual convergence and harmonisation of policy, doctrine and practice.”

The problem, he said, was that post-communist Russia “has entered a difficult and doubtful phase with Yeltsin visibly weakened and Russian democrats and westernisers on the defensive”. Even reformers, Rifkind added, “are antagonistic to Nato enlargement”.

Associate membership could be the solution. “It would most importantly provide an acceptable framework that would allow enlargement to go ahead without rancour and retaliation …

“The status of associate member would also provide the basis of a credible strategy for Nato’s relations with certain other new independent east European states, in particular Ukraine. Countries such as Ukraine, the Baltic states, Belarus and Moldova need their international status strengthened if they are not to be reabsorbed into Moscow’s embrace.”

The Foreign Office was cautious. A treaty between Russia and Nato to develop a new relationship might well be needed but the “relationship must not be based on false Russian expectations that she will, one day, become a member of the [Nato] alliance.

“We must not repeat, in the Nato context, the position the EU has got itself into in relation to Turkey – of promising the prospect of entry which it has not intention of honouring. This could be profoundly destabilising.”

Official notes drafted for the prime minister before the seminar expressed similar doubts. “What sort of relationship with Nato can we offer Russia as a price for Nato enlargement? Is the notion of associate membership, as suggested by the defence secretary, realistic? (NB important that we keep confidential the fact that we are considering the idea) …

“If Russian representatives were present at all Nato meetings, what effect would this have on Nato’s own decision-making? How much do we care about Ukraine’s or Belarus’ independence?”

Among those attending were the prime minister, John Major, Rifkind, the foreign secretary, Douglas Hurd, and the chancellor, Ken Clarke.

Minutes of the meeting show that Rifkind told colleagues current policy was not “sufficiently imaginative”. Britain “needed to decide whether we would maintain a rigid distinction between Nato and Russia … We should make Russia a more normal member of the western family. We needed to help Yeltsin make Russia a more normal European country.”

Clarke was dismissive, describing the idea of including Russia in Nato as “farcical”. The proposal did not attract support at the seminar.

Asked about his initiative this week, Rifkind said: “That was pre-Putin. We had Gorbachev and Yeltsin who were very cooperative and they were genuinely wanting to become closer to the west. Russia supported action against Saddam Hussein in the first Gulf war.

“They were unhappy about the enlargement of Nato, but didn’t make as much of a fuss about it as you’d expect … So I was trying to find a way to say could we support close cooperation with Russia, hence my suggestion of it becoming an associate member.

“Although that idea didn’t happen, it led to the Nato–Russia Council. This promoted understanding, discussion and consultation [between Nato and Russia]. Russia used to attend some Nato meetings. Sadly, this came to an end after Putin annexed Crimea.”