** iShares MSCI Turkey ETF TUR.O drops 7.8% to $30.68, a nearly two-year low

** Fund on track for weekly losses of over 20%, set for worst week since August 2018

** Slump sparked by market turmoil following Turkish authorities' detainment of Istanbul mayor Ekrem Imamoglu, President Tayyip Erdogan's main political rival, on Wednesday

** Opposition in Turkey calls move a coup attempt

** Turkish stocks .XU100 tumble, main index on track for worst week since 2008 financial crisis, dollar bonds drop

** Index of bank stocks .XBANK drops 9.6%; banking stocks make up about 20% of TUR's holdings, as per iShares data

** Central bank also suspended its one-week repo auction and hiked overnight lending rate to 46%, dashing hopes for a rate cut in April

** Paris-listed Amundi MSCI Turkey UCITS ETF LTUR.PA down 8% and set for worst week since March 2021

** TUR ETF trading at over 8% discount to net asset value, as per data compiled by LSEG

** Week's losses have erased TUR's 2025 gains; fund now down over 14% YTD

(Reporting by Lisa Pauline Mattackal)

((LisaPauline.Mattackal@thomsonreuters.com;))