Two Indian High Commission staff members posted in Islamabad went missing on Monday morning while they were out for official work, according to several news reports quoting unidentified officials.

An unidentified senior government official told Hindustan Times that India has complained to Pakistani authorities about the incident. “The Pakistani side has claimed that they are still looking into the matter,” the official was quoted as saying by the newspaper.

According to The Indian Express, one of the missing high commission staff members is a Central Industrial Security Force official while the other is a driver.

The disappearance of Indian staff members in Pakistan came over two weeks after India accused two officials of the Pakistan High Commission in Delhi of espionage and asked them to leave the country within 24 hours.

The Ministry of External Affairs had said the government declared both these officials persona non grata for “indulging in activities incompatible with their status as members of a diplomatic mission”. Pakistan’s foreign ministry, meanwhile, claimed that the Indian’s action was a clear violation of the Vienna Convention on Diplomatic Relations.

The police claimed that the two Pakistani officials, Abid Hussain and Muhammad Tahir, had told them that they had been collecting documents from informers about the movements of the Indian Army in Jammu and Kashmir. Hussain had even forged an Aadhaar card.

Pakistan has allegedly been keeping watch over several Indian diplomats over the last few days, according to NDTV. The vehicle of India’s Charge d’affaires Gaurav Ahluwalia was recently seen being followed by a bike.

In 2016, India and Pakistan had expelled officials from each other’s diplomatic missions over allegations of espionage. The same year, Pakistan arrested Kulbhushan Jadhav and claimed that he was a spy. Jadhav was sentenced to death in 2016 in Pakistan. His execution was stayed after India moved the International Court of Justice against the verdict in May 2017.