One ISI agent was held in Pune on Wednesday, while six Pakistani intruders were held in Kutch district of Gujarat on June 6 and four harcode militants, belonging to Babbar Khalsa group and trained by ISI were nabbed on June 12 in Baroda.

``We are seriously looking into the threat to key figures in the metropolis and will leave no stone unturned to ensure the safety of the citizens,'' he added.

The Police Commissioner, R H Mendonca, had announced in January this year at the annual policeconference that its one point agenda was to flush out ISI infiltrators from the city. The problem assumed serious overtones with the sustained Pakistani-backed intrusion in Kargil and Drass sectors of Jammu and Kashmir last month.

With the possibility of Pak-infiltrators attempting to sneak into Mumbai via Gujarat border, Mumbai police sounded a high alert in the sensitive areas of the city and stepped up security.

The Joint Commissioner of Police (Crime) D Sivanandan's statement that the ISI threat was real was reinforced with the arrest of an ISI agent in Pune on Wednesday and detention of two persons on Saturday for their link with the agent.

Earlier, the Maharashtra Home Department had issued an alert on June 15, cautioning people against the nefarious designs of the infiltrators to disturb peace in the state and the Chief of Naval Staff, Admiral Sushil Kumar declared that the navy was in `maximum combat readiness' for retaliation in the event of any adventurism by Pakistan.

With the Deputy ChiefMinister, Gopinath Munde calling for strict surveillance over the state's vast coastline, the government has geared up to meet the threat.