The CSTO is ready to step up mediation efforts for a compromise between Tajikistan and Kyrgyzstan, the organization's secretariat said in a statement.

"We consider unacceptable any attempts to use force to resolve contentious issues and are convinced that there is no alternative to political and diplomatic approaches. The CSTO is ready to fully increase its mediation efforts in order to achieve a sustainable compromise," reads the statement on the CSTO website.

The CSTO leaders and secretariat were saddened by the news of the September 14-17 clashes on the Kyrgyzstan-Tajikistan border and offer their condolences to the people of both countries for the tragedy, the organization says.

Large-scale fighting on the Kyrgyzstan-Tajikistan border began Friday morning. The sides accused each other of shelling. Fierce battles between the militaries of the two countries lasted all day long along almost the entire perimeter of the border. A cease-fire was achieved only by nightfall. Saturday morning the skirmishes resumed. The two sides accused each other of violating the ceasefire agreement. The exchanges of fire did not stop until Saturday evening.