EU trade commissioner Phil Hogan, a key figure in Brexit talks and one of the bloc's most senior officials, resigned on Wednesday, after a week of pressure over a breach of coronavirus guidelines.

Hogan, 60, tendered his resignation to European Commission president Ursula von der Leyen as the row rumbled on, and strong indications from the Irish government he should fall on his sword.

"It was becoming increasingly clear that the controversy concerning my recent visit to Ireland was becoming a distraction from my work as an EU Commissioner and would undermine my work in the key months ahead," he said in a statement.

His departure leaves von der Leyen in a dilemma, with Brexit talks with Britain deadlocked and a December deadline looming, and no guarantee for Ireland it will retain the powerful position.

The Irish national refused to speculate on his successor but told state broadcaster RTE the EU would "look after the interests of Ireland" in the negotiations.

There has been apprehension in Ireland at the prospect of losing a commissioner regarded as a powerful advocate for the Republic's trade interests, which threaten to be disrupted if talks fail.

Von der Leyen, who had demanded he submit a detailed report of his movements after the row erupted, said she respected his decision, thanking him for his "tireless work".

Irish prime minister Micheal Martin and his coalition partners said Hogan's resignation was "the correct course of action given the circumstances of the past week".

"We all have a responsibility to support and adhere to public health guidelines and regulations," they added, saying Hogan's replacement would be considered "in due course".

Martin's administration had said Tuesday that Hogan flouted a trio of coronavirus guidelines during a recent trip home from Brussels.

It said Hogan, propelled to trade commissioner in 2019 as the EU was in the throes of trade battles with the United States and tensions with China, broke a 14-day quarantine after arriving in Ireland and failed to limit his travel in a county in the midst of a localised lockdown.

Hogan, 60, tendered his resignation to European Commission president Ursula von der Leyen Photo: AFP / Kenzo TRIBOUILLARD

He also attended a parliamentary golf club dinner on August 19, in breach of coronavirus restrictions on social gathering numbers announced just 24 hours earlier in a bid to curb a surge in cases.

The sporting evening was attended by around 80 diners -- including a cabinet minister, a supreme court judge and lawmakers from Ireland's upper and lower houses of parliament.

It is now being investigated by police and has prompted a series of high-level resignations in Irish politics, including agriculture minister Dara Calleary and deputy chair of the upper house of parliament Jerry Buttimer.

Hogan has always denied breaking coronavirus legislation and said he tried to act in line with voluntary government guidelines.

But earlier on Wednesday Martin said the government felt anger and annoyance at "the degree to which the commissioner has undermined public confidence in adherence to the health guidelines".

"We're very clear on all three fronts he breached the guidelines," he told reporters in Dublin.

Hogan originally declined to apologise for attending the golfing event but a steady drip of revelations about his movements in the last week stoked public anger.

The scandal was compounded after it was revealed that he was pulled over by an Irish police officer for using his phone while driving.

Hogan previously claimed he was free to travel across Ireland rather than observing quarantine because he had received a negative coronavirus test.

On Tuesday he gave an interview to RTE seeming to contradict government health guidance, which asks arrivals in the country to quarantine unconditionally to account for the incubation period of the virus.

"I don't accept that -- I did everything possible to ensure that I was no risk to anybody," Hogan told RTE.

"My medical people said I was free to go."

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