TBILISI, March 7 (Reuters) - Protesters in the small ex-Soviet state of Georgia threw petrol bombs and stones at police on Tuesday night after parliament gave its initial backing to a draft law on "foreign agents" which critics say represents an authoritarian shift. Police in the centre of the capital Tbilisi used water cannon and tear gas in attempting to disperse thousands of demonstrators, who fear the draft law could hurt the South Caucasus country's hopes of European Union membership. More than 60 civil society organisations and media outlets have said they will not comply with the bill if it is signed into law