European shares sag as Greek stocks' losing streak worsens
* Greece concerns, U.S. rate hike prospects dampen sentiment
* Athens' ATG market falls 3.2 pct
* Telecom Italia up on report Vivendi to increase stake
* Rise in oil price lifts energy stocks
* Europe bourses in 2015: link.reuters.com/pap87v
* Asset performance in 2015: link.reuters.com/gap87v
By Sudip Kar-Gupta
LONDON, June 17 (Reuters) - European stock markets lost ground on Wednesday as persistent concerns over Greece's debt problems offset gains in Telecom Italia and shares in energy companies.
Traders were also reluctant to add to equity positions before a U.S. Federal Reserve meeting, with many investors expecting the Fed to signal that U.S. interest rates will be raised in September. Continuación...