A Twitter logo on an iPhone display is pictured next to a Turkish flag in this photo illustration taken in Istanbul March 21, 2014. REUTERS/Murad Sezer

ISTANBUL (Reuters) - Access to social media sites Twitter and Whatsapp was blocked in Turkey on Friday, an internet monitoring group said, following the detentions of 11 pro-Kurdish lawmakers in the mainly Kurdish southeast overnight.

Access was being blocked by throttling, an expert from the monitoring group Turkey Blocks said, a method of slowing certain websites to the point where they are unusable.