David Cameron – in a corporate headquarters – and Alex Salmond – in a chilly church hall – set out their contrasting visions for the fate of Scotland and its oil wealth on Monday.

The two leaders spent the day only a few miles apart – with the Scottish first minister hosting his cabinet before noon in the small Aberdeenshire town of Portlethen.

But as Salmond noted, for all their proximity 400 miles from London, it was unlikely that the two men's paths were going to cross.

Buoyed by successive opinion polls showing growing support, Salmond taunted Cameron from his rostrum: "If at any point David Cameron walks in, I am available for this debate," he said, to chuckles from the largely middle-aged audience. "I'm here, I'm ready, I'm willing. Let's take the opportunity to exploit this geographical coincidence in order to pursue the debate that so many people in Scotland want to see."

He added: "The UK cabinet has come to Aberdeen but they're not going to have any public discussion or access. It does seem a wasted opportunity, not just for the first minister and the prime minister to debate, but to have people from this area question the UK cabinet over its range of responsibilities."

Three hours later, just under six miles to the north of Portlethen, Cameron chaired a cabinet meeting in the security and privacy of Shell's plush regional headquarters.

David Cameron, centre, visits a North Sea oil platform 100 miles east of Aberdeen on Monday. Photograph: Reuters

The prime minister had arrived in Aberdeen on board an RAF jet, flown across the North Sea for an exclusive tour of a BP oil platform, before his convoy swept into the vast Shell complex, where vast car parks were full of BMWs, Audis and Range Rovers.

As the two governments traded press releases proving their commitment to North Sea oil, it was as close as the two men came.

After the battles earlier this month over the chancellor George Osborne's veto of a sterling currency union, backed by Labour and the Liberal Democrats, the future of the UK's oil reserves became the latest proxy in the war over the independence referendum in September.

Ed Davey, the UK energy secretary, went to Peterhead where he confirmed he had authorised a "fast-tracked" programme to squeeze another £200bn worth of oil and gas from the North Sea on the recommendation of Aberdeen oil magnate Sir Ian Wood.

At Shell's large Peterhead gas-fired power station, Davey was joined by Nick Clegg, the UK deputy prime minister, and Alistair Carmichael, the Scottish secretary, to say that the plant had, after years of delay, won £50m in funding to prepare itself for a carbon capture and storage project.

The Department of Energy and Climate Change pressed home the case that North Sea oil reserves were in permanent decline – a clear risk to the Scottish economy: it had fallen 40% in the past three years, while production efficiency had fallen to 60%, costing the economy £6bn.

Salmond retaliated by unveiling a parallel £10.6m scheme to create a new oil industry innovation centre in Aberdeen, backed by academics from 12 Scottish universities. It will promote new techniques to maximise oil recovery from old fields, exploit shale gas and extend the lifetime of rigs.

t was the education secretary, Michael Gove, who spent the most time of any Tory cabinet minister with the media. He was brought up in Aberdeen and told reporters he had spent the past four days in the city with his parents, drinking in his old local, the Prince of Wales, and meeting children at his old primary school, Kittybrewster.

Gove described Salmond as "rather sneery" and said: "Part of the problem with Alex Salmond's approach is that he constantly seeks to divide and he poses as the father figure of the Scottish nation but, in fact, what he wants to do is set brother against sister."

Earlier, Salmond hinted that an independent Scotland could use sterling regardless of a currency union and spoke contemptuously about Cameron's grasp of oil industry economics. The first minister told BBC Radio 4's Today programme that he had been working as an oil economist when Cameron "was fooling around on the playing fields of Eton".

Salmond repeated his demands for Cameron to agree to a face-to-face television debate on independence but, in his selective television interviews,

Cameron dismissed the challenge and repeated that he had no vote in the referendum. "The debate that needs to take place is the debate in Scotland between people of differing views," he said.

The prime minister hinted at one reason for refusing Salmond's demand: his party's unpopularity in Scotland.

He admitted he had been delighted at rock star David Bowie's plea at last week's Brit music awards for Scottish voters to reject independence. He told the BBC: "When I saw Kate Moss leap to the stage and utter those words I have to say I did let out a cry of joy because I'm sure that maybe someone like David Bowie might be able to reach parts of Scotland that perhaps I can't."

• This article was amended on Monday 24 February 2014 as it stated that Peterhead is in Alex Salmond's Holyrood constituency. The town is in Stewart Stevenson's Banffshire and Buchan Coast constituency.