UPDATE 1-EU states seek more time on S.Korea pact-diplomats

* EU needs more time to decide on $100 billion S.Korea pact

* Initialling deal seen unlikely at May 23 EU-S.Korea summit

* Political signal sought at summit, deal before summer

* States seek more details on "duty drawback" safeguards

(Adds quotes, details)

By Darren Ennis

BRUSSELS, May 8 (Reuters) - The initialling of a $100 billion trade pact between the European Union and South Korea is unlikely to take place this month after EU states asked for more time to give political assent, diplomats said on Friday.

"A number of member states have asked for more details. Initialling at the summit is unlikely. A deal before the summer break is a more likely outcome," an EU source with knowledge of Friday's meeting of EU trade officials told Reuters.

EU and South Korean leaders will hold a summit on May 23 in Seoul to seek a final breakthrough in the talks aimed at lowering barriers to trade and investment. A deal with Seoul would be the EU's first such pact in Asia.