DUSHANBE, May 28, 2013, Asia-Plus -- An informal summit of the Collective Security Treaty Organization (CSTO) has opened in the Kyrgyz capital, Bishkek, Radio Liberty reports.

The presidents of Kazakhstan, Kyrgyzstan, Russia, and Tajikistan will discuss the situation in Afghanistan as U.S.-led international forces prepare to withdraw in 2014.

The plan to build a railroad that would connect Russia with Central Asia and later with Afghanistan and the Persian Gulf has been also included on the summit''s agenda.

Before the opening of the summit, Russian President Vladimir Putin and his Kyrgyz counterpart, Almazbek Atambayev, discussed prospects for bilateral cooperation.

The Kyrgyz president''s office said discussions included Moscow''s involvement in the construction of Kyrgyz hydropower stations and military cooperation.

The presidents of two CSTO member states, Armenia and Belarus, are not taking part in the summit.