One of Africa's most eminent political figures has condemned Britain for taking a patronising "big brother" attitude to its former colonies.

Graça Machel, a founder member of the Elders group of world leaders and the wife of Nelson Mandela, warned British politicians to "keep quiet" about countries such as Zimbabwe and let African diplomacy take its course.

Machel, 64, is a former first lady of Mozambique, where she served as education minister, and has won numerous international awards for her advocacy of women's and children's rights.

In an interview with the Guardian in Johannesburg, she indicated that the crisis in Zimbabwe has revealed the shortcomings of a persistent imperialist mindset.

"Can I be a little bit provocative?" Machel said. "I think this should be an opportunity for Britain to re-examine its relationship with its colonies. To acknowledge that with independence those nations will want to have a relationship with Britain which is of shoulder to shoulder, and they will not expect Britain to continue to be the big brother.

"When a nation is independent, there is no big brother. They are partners. Part of the reason why Britain finds it difficult to accept Zimbabwe is precisely because that relationship of a big brother is influencing [efforts] to try to understand."

Britain, along with the EU and US, has imposed travel restrictions and asset freezes on Zimbabwe president Robert Mugabe and his political and business allies. It has defied calls from South Africa to end these measures for the sake of the power sharing agreement between Mugabe's Zanu-PF and the Movement for Democratic Change (MDC).

Earlier this year David Miliband, the foreign secretary, said the UK would be "guided by what the MDC says to us about the conditions under which it is working and leading the country". Critics said this handed Zanu-PF a propaganda coup, allowing it to portray the MDC as a puppet of Britain and blame it for sanctions.

Machel added: "I'm not saying things are OK, they're all fine in Zimbabwe. I'm saying a different kind of dialogue, a different kind of bridge to try to understand the other side could have produced a different result from what it is.

"The more the British shout, the worse the situation will be in terms of relationship with Zimbabwe. That's why sometimes I really question, when something happens in Zimbabwe and Britain shouts immediately. Can't they just keep quiet? Sometimes you need just to keep quiet. Let them do their own things, let SADC (Southern African Development Community) deal with them, but keep quiet, because the more you shout, the worse [it is]."

Asked if Britain's attitude is patronising to its former colonies, Machel replied: "I'm afraid so. And what I'm saying is they have expectations which do not always coincide with what are the aspirations and expectations of those who are their former colony.

"When you change the relationship, you just have to give yourself to take the humility to stop and listen. And when you listen, then you take into account the other side. You put your case, then you take the other side. In a way, you harmonise interests of both sides."

Zimbabwe will mark 30 years of independence this weekend. Britain remains politically and economically influential and denies Mugabe's claim that it reneged on promises to fund the redistribution of land to the black majority. Mugabe's response, the chaotic seizure of white-owned farms, has been blamed for the collapse of Zimbabwean agriculture.

Machel, whose first husband was the late Mozambique president Samora Machel, called on Britain to take a broader view of the African continent. "That's one of the issues, particularly with the British people: because of the emotional attachment they have with Zimbabwe, in many cases they define the continent in terms of Zimbabwe. Zimbabwe is one country among 53 countries, so you have all the rest of 52 countries. Well, let us put aside Somalia also, which is a failed state. But you have 50 countries who are running a relatively normal situation in the continent.

"I would like to raise with you the issue that yes, Zimbabwe has failed, and it is hurting British people directly, but there's much, much more to Africa than Zimbabwe."

Machel, who became Mandela's third wife in 1998, also accused developed countries of double standards on CO 2 emissions and climate change.

"This has been very clearly stated at the negotiations to Copenhagen. They know – the developing world, including China – that Africa has very small responsibility in the impact of climate change, but Africa is the one paying the highest price."

Britain's intentions are still treated with scepticism in Zimbabwe, even among some members of the MDC. Eddie Cross, policy co-ordinator general of the MDC, said: "Perfidious Albion. I tell you, you Brits have a well-deserved reputation for perfidity in your colonial relations … I think Britain's always been very sophisticated in its relations with its former colonies – it's got more experience than any other state in the world – but it doesn't necessarily make them right.

"Britain's role in the last 10 years has often been difficult for us in the MDC to interpret and read. Sometimes they've backed certain initiatives in Zimbabwe which have not been helpful in terms of pursuing a principled transfer of power and I think sometimes the Brits regard us as being rather naïve in the MDC and they have a rather jaundiced view of Africa and African politics."

But Cross, an economist and MP, added that other European powers probably behaved worse: "Samora Machel once said to me: 'If you were to choose to be colonised, you would never choose to be colonised by the Portuguese.' The colonial record was pretty dismal. For the British it was probably the best."