(Adds comments on Gulen, background)
By Gulsen Solaker
ANKARA, Aug 14 (Reuters) - Turkish president-elect Tayyip Erdogan urged his AK Party on Thursday to secure a stronger parliamentary majority next year to enable them to re-write the constitution, signalling no let-up in his drive to strengthen the presidency.
Erdogan secured his place in history as Turkey's first directly elected head of state on Sunday, taking him a step closer to the presidential system he covets for the European Union candidate nation and NATO member state.
His opponents fear an increasingly authoritarian state under Erdogan, who has dominated Turkish politics for more than a decade, and whose Islamist roots and intolerance of dissent they fear is taking Turkey further away from Western values.
"I said before that the presidential elections would be the starting gun for the 2015 (general) elections," Erdogan told a meeting of AK Party provincial leaders in a speech broadcast on Turkish television.
"Our target should be to acquire at least a majority to establish the new constitution. I don't believe that you will compromise on this," he said.
Erdogan will have to break formal links with the AK Party he founded 13 years ago once he is sworn in as president on Aug. 28. He wants a pliant successor as leader of the party, likely also to be his next prime minister, in order to secure a stronger parliament majority in polls next June.
Should his influence over the party wane, Erdogan could struggle to force through the constitutional changes he wants to create an executive presidency - a reform which requires either a two thirds majority in parliament or a popular vote.
The AK Party currently holds 313 of parliament's 550 seats, a strong majority but below the crucial two thirds threshold.
In his first major speech since declaring victory in Sunday's election, Erdogan vowed to continue his battle with influential U.S.-based Islamic cleric Fethullah Gulen, whom he accuses of seeking to overthrow him.
Erdogan accuses Gulen's supporters in the judiciary and police of contriving a corruption scandal which burst into the open last December as part of a plot to undermine him.
Thousands of police officers and hundreds of judges and prosecutors have been reassigned in a purge of Gulen's influence since then, with Erdogan accusing what he calls a "parallel structure" of a "vile betrayal" of Turkey.
"It's an organisation that threatens our national security. We have new evidence, new files," he said on Thursday.
"(Their) targets are not Recep Tayyip Erdogan, his family, his colleagues, his friends. Their target is our independence, our flag, our country and our people." (Additional reporting by Selin Bucak and Ece Toksabay; Writing by Nick Tattersall; Editing by Crispian Balmer)