India says it will expel a Pakistani diplomat it accuses of being the “kingpin” of a spy ring, after his arrest on Wednesday outside the gates of the Delhi zoo, where police allege he was planning to meet Indian contacts he had recruited.

Tensions between the nuclear-armed neighbours are at their highest for more than a decade after 19 Indian soldiers were killed in Kashmir last month in an attack by militants that Delhi accuses Islamabad of sponsoring.

Police said the official, named as Mehmood Akhtar, and two Indians also arrested were carrying forged documents, lists of army officers stationed at the India-Pakistan border and maps showing Indian troop deployments.

Akhtar, who reportedly worked in the visa section of Pakistan’s high commission, has been released by police in line with agreements on diplomatic immunity, but has been declared persona non grata.