Andy Burnham has promised a “serious dialogue” over the UK’s future place in Europe, saying the existing relationship is “not good enough” as he framed next month’s Brussels summit as a possible first step to EU membership.

The prime minister said Britain must take a “clear-eyed rational look” at its long-term relationship with the bloc to boost economic growth and control immigration, which needed to go beyond Labour’s existing red lines.

The next “reset” summit will take place on 20 November, ending months of uncertainty, with the two sides seeking to sign deals on food and drink, youth mobility and emissions trading, which Burnham hopes could provide a £10bn-a-year boost to the economy.

One EU diplomat said a deal on the three “significant but modest” issues needed to be approved as a test of the UK’s good faith so that both sides could get on with the “real reset” in the longer term relationship.

But the UK remains braced for a possible row over protectionist “Made in Europe” trade rules amid industry fears they could lock out UK manufacturers, prompting the prime minister to pledge he would raise concerns with his EU counterparts.

Burnham was also forced to clarify that he did not think Russian interference in the 2016 Brexit campaign had affected the final result, after he raised questions about the legitimacy of the outcome in comments at the weekend.

In a statement to MPs, the first since the party conference recess, an otherwise confident-sounding Burnham said it would be a “major dereliction of duty” for his government to turn away from exploring closer relations with the EU.

“We should not turn our backs on this opportunity and I hope all sides of this house will get behind the government’s efforts to land a positive outcome,” he said.

“I believe our chances of doing so will be enhanced by being open to a discussion about our relationship with the EU in the longer term. If we are serious about promoting growth, controlling immigration, upholding our values and security, it is a conversation we must have.

“Sticking with the status quo is not good enough for Britain. Worse, it would be a major dereliction of duty to turn away. We need to take a calm, clear-eyed, rational look at the world as it is today to consider what is best for our country.

“Our immediate priority is securing a successful outcome at the summit, and I believe we should then set up a serious dialogue about the different options for our relationship in the long term.”

Burnham denied he was reopening the Brexit debate, insisting he did respect the referendum result, but added that he wanted to take a “pragmatic approach” to boost economic growth and improve cooperation on migration.

He was forced on to the back foot over his remarks to a podcast on Sunday that Russia had interfered over Brexit, rejecting suggestions from Kemi Badenoch, the Conservative leader, that he may have been loose with his language.

“It is a matter of record that Russian actors sought to interfere in the 2019 general election, and we think it is inconceivable that this was the first time,” he said.

Burnham had said on Sunday it was clear that Russia had interfered in the 2016 Brexit referendum after he sought answers when he arrived in No 10. He did not disclose who gave him the assessment, what evidence it was based on or, crucially, whether any interference had affected the result.

Downing Street said the prime minister “absolutely” accepted the Brexit referendum result and believed it to be legitimate, while the foreign minister Stephen Doughty said it was clear Russia had attempted to interfere but had failed.

In his statement, Burnham told MPs they had been right to raise the question of the “loss of immigration control” that came with Brexit, as Labour grapples with continuing public concern over the issue, and suggested Brussels recognised this.

The UK is excluded from Eurodac, a database which holds biometric and ID data to identify asylum seekers and irregular migrants, and exited the Dublin regulation, a legal mechanism to return refugees to the European country through which they had first entered or transited.

But while the prime minister told MPs a return to free movement was “not on the table” in his discussions with the EU, and said he would honour Keir Starmer’s manifesto red lines, he was unable to rule it out for a post-election future.

Sources on both sides believe they will be able to get other issues over the line at the summit next month, suggesting that a food and phytosanitary agreement would have been reached in July if the summit had gone ahead on its original date.

Issues still to be resolved include a transition period for grains grown in the UK using recently approved fungicides not yet licensed in the EU. This would allow farmers harvesting this year to sell stockpiles next year even with the different regulations.

The thorniest issue remains the youth mobility programme, allowing EU and British citizens under 30 to live, work or study in each other’s countries for up to three years. The two sides are at odds over the overall numbers, as well as the tuition fees students would pay at British universities.

The biggest current risk to the UK of not aligning more fully with the EU is being locked out of the new Made in Europe initiative – aimed primarily at imports from China in strategic sectors such as renewable energy, nuclear and electric cars – which will block British-made components being used in EU supply chains.

EU sources have insisted there can be no agreement on the issue with the UK at the summit, because the bloc is yet to agree its own position on the proposals. EU lawmakers hope to agree a position on a key proposal, the Industrial Accelerator Act, in December.

But Brussels is, at least, open to discussing the issue, and it may be part of the summit statement – a joint text agreed by both sides. The UK has the support of the Netherlands, Poland and Italy for inclusion in the scheme, but France in particular has posed a stumbling block.

Burnham acknowledged that Made in Europe presented “risks” to British manufacturing, perhaps in an attempt to address some concerns inside government that Downing Street hasn’t been prioritising the issue.

He said: “It is important that we get to an arrangement here that works for both the UK and the EU. After all, we’re both trying to deal with the same issue, which is Chinese exports and the damaging effect that is having on our industry.”