The disappearance of an elderly Cape Town couple in KwaZulu-Natal more than a week ago and an update by the UK Foreign and Commonwealth Office to a terrorism travel advisory to South Africa caused diplomatic strain between the two countries this week.

South African officials accused the UK of acting in haste and exaggerating.

The department of international relations and cooperation wrote to the UK High Commission in Pretoria on Friday, asking it to review the update.

Spokesperson Clayson Monyela said: “The department is concerned at the removal of the sentence that ‘there have been no terrorist attacks on South Africa in recent years’, which had appeared in previous iterations of the Travel Advice.”

The department was unhappy that the suspected kidnapping of the couple, who hold dual South African and UK citizenship, was linked to terrorism.

In June 2016 the UK and US governments issued travel advisories on possible terrorist attacks on their nationals, leading to an open diplomatic spat with South Africa.

Twin brothers Brandon-Lee and Tony-Lee Thulsie were arrested shortly after on terrorism charges, but their court case is still ongoing.

Authorities have so far been mum about the details of the suspected kidnapping case, including the identity of the missing couple, whose car was found on Wednesday.

Hawks spokesperson Captain Lloyd Ramovha said that revealing details about the case could “derail the investigation and endanger lives”.

Although the Hawks said more arrests were imminent, “possible suspects” Sayfydeen Aslam Del Vecchio (38) and Fatima Patel (27), appeared briefly in the Vryheid Magistrates’ Court on Monday and are expected to appear again on Thursday.

The charges they face include “kidnapping, alternatively robbery and arson”, in respect of several hectares of Tongaat Hulett sugarcane fields, worth R2 million, they torched in 2017, and the “possible contravention” of the Protection of Constitutional Democracy Against Terrorist and Related Activities Act of 2004.

It’s also believed Islamic State propaganda was found at Del Vecchio and Patel’s base in Ballito, on the KwaZulu-Natal north coast.

Patel was already under watch following her arrest in a July 2016 counterterrorism raid in which the Thulsie twins were arrested.

A government official said the couple, reported by The Guardian to be a 74-year-old Briton who moved to South Africa in the 1970s and his South Africa-born wife (63), were travelling to collect plants for their business in Cape Town.

They were suspected to have been kidnapped around the Bivane Dam near Vryheid, a popular local spot for boating and bass fishing.

They were apparently made to withdraw large sums of money from their bank accounts but, the official said, this was put to personal use and not to fund terrorist organisations.

Independent analysts said the suspected kidnapping did not bear the hallmarks of terrorism.

Jasmine Opperman from the Terrorism Research and Analysis Consortium wrote in the Daily Maverick that if this were related to terrorism, members of the “cell” might already have been in touch about ransom demands, she said, concluding that “the true intention of the KwaZulu-Natal cell kidnap/hostage-taking is unclear and the known facts are too insufficient to hazard a guess”.

Spokesperson for the State Security Agency Brian Dube agreed, saying the update to the UK travel advisory was “really a non-issue”.

He said: “There is no evidence at this stage indicating any serious terrorism links to the issue.

“The Hawks are dealing with it,” Dube said.

He said the agency didn’t release a statement because “we don’t want to raise the issue unnecessarily”.

Dube said the department of international relations met officials from the UK High Commission this week to discuss the issue.

Intelligence agents also met.

He said authorities would inform the public of any possible terror threats, but this was not necessary right now.

The UK High Commission said: “We have updated our travel advice to include this recent incident.

“The safety of British nationals is our top priority. We keep our travel advice for all countries under constant review. We update it as quickly as possible if we’re aware of an incident that might significantly affect Britons travelling or living in the area.”