The Irish government has hit back at “misinformation” and “pressure” from Britain as talks over a Brexit deal tottered towards collapse.

Simon Coveney, Ireland’s foreign minister, said on Tuesday that his administration was working “flat out” for a deal, despite accusations from Downing Street that Dublin had virtually sabotaged any chance of compromise.

“No country wants a deal more than Ireland but we will not strike a deal at any cost,” he told a press conference in the Irish capital.

Boris Johnson spoke to his Irish counterpart, Leo Varadkar, on Tuesday evening. Downing Street said that “both sides strongly reiterated their desire to reach a Brexit deal” and hoped to meet in person later in the week.

However when Coveney was asked earlier about the Downing Street briefings that accused Varadkar of derailing talks with inflexibility over the backstop, he said there had been a “lot of misinformation” and an attempt to pressure Ireland.

Without naming Johnson, Dominic Cummings or any other figure in the British government, Coveney said there were “conflicting reports” from London and “a hard line” from those briefing the media.

Coveney said that Ireland had welcomed Johnson’s Brexit proposals last week as a “step forward” while stressing that more work was needed to find a solution.

“There is an ongoing conversation in Brussels and we want to contribute to that in a constructive way ... the taoiseach wants to find a compromise that works. But he is not willing to be boxed into a corner.”

Dublin had been “upfront and honest” in highlighting problems with Downing Street’s plan, said Coveney. “We can’t pretend we’re solving problems when we’re not.”

The foreign minister, who doubles as deputy prime minister, said a blame game seemed to be eclipsing a search for solutions: “But this is too enormous an issue to be focusing on the politics of blame.”

Coveney was due later to travel to Brussels to meet Michel Barnier, the EU’s chief Brexit negotiator.

EU and Irish officials have criticised Downing Street’s plan as unworkable for taking Northern Ireland out of the EU’s customs union and for giving the Democratic Unionist party (DUP) a veto over trading arrangements.

On Tuesday, a No 10 source accused the German chancellor, Angela Merkel, of making a deal impossible. Brussels responded by accusing Johnson of trying to play a “stupid blame game”.

Despite Coveney’s insistence that a last-minute deal was still possible, there was a growing sense of dread in Dublin that no-deal Brexit was edging closer, heralding political instability in Northern Ireland and economic pain on both sides of the Irish border.

Ireland’s finance minister, Paschal Donohoe, warned of turbulence while presenting the annual budget to the Dáil on Tuesday. “This is a budget that has been developed in the shadow of Brexit,” he said.

The country has enjoyed strong growth and tax receipts, but Donohoe said the increasing likelihood of the UK exiting the EU without a deal posed a “pressing and immediate risk” to Ireland’s economy.

The government deferred tax cuts and allocated €1.2bn, excluding EU funding, to cushion any shock. Donohoe earmarked €650m to support the agriculture, enterprise and tourism sectors, as well as regions that would be most affected by a no-deal Brexit.

At sombre press conferences following the budget announcement, successive ministers detailed their departments’ no-deal Brexit contingency plans. One minister referred to the preparations as “triage”.

The teetering Brexit talks have caused the gulf between political parties in Northern Ireland to widen.

Arlene Foster, the DUP leader, claimed that an Irish plot had been exposed. “The prime minister’s proposals have flushed out Dublin’s real intentions to trap Northern Ireland in the EU customs union forever, where Dublin rather than the United Kingdom’s elected representatives would be in the driving seat.”

Sinn Féin’s deputy leader, Michelle O’Neill, accused the DUP and “other delusional Brexit cheerleaders” of exposing Northern Ireland to potentially catastrophic consequences.

“The north’s economy cannot withstand being excluded from the customs union and the single market, and that is the message we will be bringing loud and clear to the EU.”