Brexit is certainly going to have an impact on cybersecurity ties between London and Brussels, but the move to snub Britain at a major meeting before its departure from the union could signal more hurdles for British diplomats should another Brexit extension be agreed upon in future.

In a rare move, British diplomats were excluded from an EU meeting on cybersecurity, even though the UK is still part of the European Union, the Financial Times reports.

Tim Barrow, the UK's permanent representative to the EU, wrote a letter of complaint to the European Council on Friday, protesting against British officials being “disinvited” from the 25 June meeting on EU-wide cyber security standards.

He reportedly said that the move raised “questions and concerns in London with regards to the treatment and process around meetings at 27 and 28 during the current extension”.

The UK has yet to leave the union, with the latest formal date of departure set for 31 October, but speculation is floating around that Brussels is mulling another Brexit extension to avoid a no-deal scenario.

For the time being, Britain still is a full-fledged member of the bloc, and as such, has the right to take part in discussions on a variety of topics, including sensitive issues like cybersecurity and intelligence-sharing.

EU officials, however, have the right to bar their UK counterparts from meetings under ‘exceptional circumstances’ – for instance, when discussing matters pertaining to Britain’s withdrawal process.

However, Barrow did not think that was the case here.

“In respect of the disinvitation to the meeting on 25 June, the UK has received no explanation as to the substantive reason for its exclusion. We are therefore unable to accept the threshold for ‘exceptional circumstances’,” he was quoted as saying.

In the letter, he also denied that “UK involvement risked posing a threat to the essential security interests of the Union”.

The meeting participants are understood to have discussed ways to protect Europe’s nascent 5G mobile internet networks amid espionage risks potentially posed by Chinese tech company Huawei.

It emerged in April that Britain’s top security officials, including the PM, had agreed to allow Huawei to take part in its 5G build-up. This week, lawmakers said there were no technical grounds for banning Huawei entirely from Britain's 5G networks.

However, as the UK is facing pressure from the Trump administration over Huawei and is awaiting the appointment of another prime minister, the government has yet to make a final decision on Huawei so far.

Last year, alongside other fellow EU members, Britain incorporated into national law the General Data Protection Regulations (GDPR) – Europe’s new framework for digital privacy and data protection standards.

London has committed to keeping its data protection framework aligned with the bloc post-Brexit, and the European Commission will issue an “adequacy assessment” on whether British standards comply with the European ones.