New Delhi, Feb 19 Tightening up visa procedures, the Home Ministry on Thursday asked all central ministries and state chief secretaries to strictly adhere to the revised procedure for grant of visas to foreigners coming to India to attend international conferences and seminars.

Security clearance for grant of conference visa will be required for participants from Afghanistan, Bangladesh, China, Iran, Iraq, Pakistan, Sri Lanka, Sudan and in respect of foreigners of Pakistani-origin and stateless persons, the Home Ministry said in a statement.

"These instructions have been issued so as to ensure that all organisers of such international events strictly adhere to the time line for submitting their proposals to this ministry at least six weeks before the commencement of the event," the Ministry said in a statement.

"This would ensure that security clearance for the event and for the participants could be suitably assessed. The issuance of these instructions had also become necessary because security vetting is a time-consuming process and most of the organisers of international events were not strictly adhering to the time schedules prescribed."

Participants from other countries can obtain a conference visa from the Indian mission concerned on production of an invitation letter from the organiser, event clearance from the home ministry, administrative approval of the nodal ministry and political clearance from the Ministry of External Affairs.

In December, the home ministry had issued directions through the External Affairs Ministry to all missions abroad that any applicant for an Indian visa who has any sort of Pakistani lineage, even if it is two generations back, must be referred to Delhi for prior clearance.

This was after Laskhar-e-Taiba suspect David Coleman Headley, currently in detention in the US, made use of a multiple-entry business visa to make nine trips to India that included long periods of stay when he prepared footage of 26/11 targets.