Indian and Pakistani officials are holding talks in Delhi on the fight against drugs smuggling.
Both countries are concerned over Afghanistan's opium production
The two-day meeting is part of wider efforts to improve relations between the South Asian rivals.
On Tuesday, officials from both sides will meet in Islamabad to discuss putting in place safeguards to avert a possible nuclear conflict.
The nuclear-armed rivals, who have fought three wars since independence, embarked on a peace process in January.
The five-member Pakistani delegation is being led by its Anti-Narcotics Force director general, Maj Gen Nadeem Ahmed.
"We have to fight the war against narcotic drugs together. It is a common cause, has no borders and has no political considerations," Gen Ahmed told the Press Trust of India.
He and his Indian counterpart, Narcotics Control Bureau chief Swaraj Puri, discussed joint ways to detect and control the spread of drugs such as heroin.
Both India and Pakistan are used as transit routes for heroin sourced from Afghanistan.
Pakistan forms part of the notorious Golden Crescent, along with Iran and Afghanistan - the world's leading opium producing region.
Gen Ahmed also met Indian Home Minister Shivraj Patil and said both countries should help each other crack down on drug smuggling.
"We have to see what the laws of each country allow," the AFP news agency quoted him as saying.
Later on Monday, a five-member team from India were to arrive in Islamabad for the nuclear talks.
"Their focus will be on formalisation of an agreement on prior notification of ballistic missile tests, and how to ensure conventional stability," Pakistan foreign ministry spokesman Masood Khan said.
He also said that Islamabad found Indian objections to US arms sales to Pakistan "disturbing".
"India's weapons acquisition and weaponisation programme is very ambitious. They have been buying weapons and sophisticated technology from all over the world."
The Indian government voiced its concern at the US selling F-16 fighter aircraft to Islamabad during a visit last week to Delhi by US Defence Secretary Donald Rumsfeld.
India and Pakistan have held several rounds of talks but have made little progress on the main bone of contention, the dispute over the Himalayan territory of Kashmir.
Last week, the two sides failed to resolve differences over starting a proposed bus service linking Indian-administered Kashmir with the area under Pakistani administration.
A proposed Kashmir bus service has failed to take off
The service was halted after the first war between the two countries in 1947, and families divided by the Line of Control (LoC), the de facto border between the countries, have been demanding its resumption.
But correspondents say restarting it is fraught with diplomatic and political difficulties.
India wants passengers to use passports, but Pakistan is said to favour less formal travel documents, as the use of passports and visas would imply recognition of the LoC as a permanent border.