The EU has welcomed Turkish PM Recep Tayyip Erdogan's election victory, and urged him to relaunch reforms which could lead to membership of the bloc.
Mr Erdogan's AK Party increased its share of the vote by 12%
EU Enlargement Commissioner Olli Rehn said a new Turkish government would need to make "concrete progress" on freedom of expression and religion.
Mr Erdogan has pledged to "work with determination" towards EU membership.
He won a second five-year term in office after his AK Party increased its share of the vote to 46% on Sunday.
The election was called after opposition parties in parliament blocked the AKP's nominee for the post of president, causing political deadlock.
But despite his electoral victory, Mr Erdogan will lack the two-thirds majority in parliament needed to be able force through his candidate.
'Major challenges ahead'
On Monday, the EU officials congratulated Mr Erdogan on his party's victory, describing it as a mandate for the reforms it wants Turkey to complete during its membership talks.
However, the bloc's enlargement commissioner said the new Turkish government faced "major challenges ahead".
"It is essential that the new government will relaunch the legal and economic reforms with full determination and concrete results," Mr Rehn said.
"We need to see concrete progress on such fundamental freedoms as the freedom of expression, the freedom of religion."
The president of the European Commission, Jose Manuel Barroso, also welcomed the victory, saying the vote came "at an important moment for the people of Turkey".
The UK Foreign Secretary, David Miliband, said it was very important for Europe to "reach out" to the new government.
"A stable and secure political situation in Turkey is massively in our interest and we will certainly want to be taking forward our links with this very important country," he added.
Austrian Foreign Minister Ursula Plassnik said everyone was interested in having a "modern, dynamic, successful Turkey as a partner".
"We expect this government that has a good track record over the past years to continue with even more ambition," she said.
Correspondents have warned, however, that Mr Erdogan's mandate for reform may be limited by the workings of the Turkish electoral system.
Although the AKP has been returned to power with a larger share of the vote - 12 percentage points more than in 2002 - its share of the seats has dropped to 340 out of the 550 in parliament.
The main secularist opposition group, the Republican People's Party, also increased its share of the vote, but its number of seats fell by more than 60 to 112.
The two main parties have fewer seats because the right-wing Nationalist Action Party (MHP) passed the 10% threshold to enter parliament, unlike in 2002.
This time, the MHP won 71 seats with 14% of the vote.
No other parties passed the threshold, although 28 independent candidates, including more than 20 members of the Kurdish Democratic Society Party, won seats.
It is the first time in more than a decade that a Kurdish party is represented in parliament.