Ankara - Pakistan President Asif Ali Zardari and his Afghanistan counterpart Harmid Karzai were in Istanbul Friday for a summit to discuss ways to improve regional security.

The two leaders are expected to concentrate on tensions over Pakistan's north-western tribal regions, which have become a base and recruiting ground for hardline Taliban fighters bent on overthrowing the Afghanistan government.

Discussions are also expected on preventing drug smuggling and organized crime.

Friday's meeting was the second summit between the leaders of the neighbouring countries, with Karzai holding talks in April last year with then Pakistani president Pervez Musharraf.

In addition to the bilateral summit, the leaders will also hold talks with Turkish President Abdullah Gul. (dpa)