By Tom Perry and Laila Bassam
DAMASCUS (Reuters) - Damascus aims to secure Syria's border with Turkey and recapture the city of Aleppo with its latest military offensive, a top adviser to President Bashar al-Assad said on Tuesday.
In an interview in her Damascus office, Bouthaina Shaaban held out little hope for diplomatic efforts to end the five-year civil war, telling Reuters proposals for a ceasefire were coming from states that "do not want an end to terrorism" and wanted to shore up insurgents who are losing ground.
The Syrian army, backed by Russian air strikes and Iranian and Lebanese Hezbollah fighters, has launched a major advance in recent weeks near Aleppo, once Syria's biggest city, now divided between rebel- and government-held sectors.
The offensive, one of the biggest shifts in momentum of the five year civil war, has brought government forces closer than they have been in years to a border crossing with Turkey that has served as the main supply route into rebel-held territory.
There would be no letup in an army advance, which aimed "to liberate cities and villages that were controlled by the terrorists for 3-1/2 years, and also an attempt to liberate the city of Aleppo from the crimes of terrorism", Shaaban said.
Damascus intended "to control our borders with Turkey, because Turkey is the main source of terrorists, and the main crossing for them".
The United Nations said on Tuesday it was worried about the fate of up to 300,000 people still living in rebel-held parts of Aleppo, who could be cut off from food supplies if the government advance succeeds in surrounding the city and blocking access from Turkey.
Tens of thousands of people have fled the area, and Turkey, which has already taken in 2.5 million Syrian refugees, has so far mostly kept the border closed to them, despite U.N. calls to allow them to flee.
Shabaan said Turkey was using the refugee crisis to blackmail European states, criticizing Ankara and its "Ottoman ambitions" as the prime cause of the war that has driven 11 million people from their homes and killed 250,000 people.
The Syrian army and its allies have gained ground in recent weeks in the provinces of Latakia and Aleppo, which border Turkey to the north, and Deraa, which borders Jordan to the south. They have also advanced against Islamic State to the east of Aleppo.
The advance helped derail the first peace talks in two years, which collapsed last week before they had begun in earnest, with rebels demanding a halt to bombardment - something the Syrian government criticized as pre-conditions for talks. International powers are expected to meet later this week to revive diplomacy, with Washington seeking a truce.
The gains have helped to tip the momentum Assad's way after Damascus lost ground last year to an array of insurgents in western Syria including the al Qaeda-linked Nusra Front, other Islamist groups, and "Free Syrian Army" rebels that have received U.S. backing.
The Syrian government describes all the groups fighting it as terrorists.
"We hope that the operation will continue in the north until we control the borders and stop the terrorists who Turkey has since the start of the crisis worked to send to Syria," Shabaan added. Asked if military operations would continue at the same pace, she said: "Certainly, God willing".
U.N.-led efforts to launch peace talks in Geneva last week were suspended as the government offensive gained ground. U.N. envoy Staffan de Mistura aims to reconvene the talks later this month. However, diplomats say they have little hope for a resumption of talks as long as the Russian-backed government offensive is under way full bore.
Shaaban said she did not expect success for diplomacy, saying the problem remained one of foreign support for militants in Syria and if there had been "a real international desire" to end the problem the crisis would been resolved years ago.
"The states that support terrorism in Syria, behind the financing and weapons, did not take a decision to halt this financing and arming, and therefore we do not see success for the diplomatic efforts", she said.
Alongside Turkey, Saudi Arabia has been a major sponsor of the insurgency that grew out of an uprising against Assad's rule.
Before the start of any negotiations, the opposition has demanded a halt to airstrikes and a release of detainees. The Syrian government has said it did not impose any preconditions and would not implement any preconditions before talks.
U.S. officials have said Secretary of State John Kerry will push to secure an immediate ceasefire and aid for civilians ahead of a meeting of powers in Munich this week.
Shaaban said: "I believe the talk of a ceasefire is to avoid the main thing that must be done, which is fighting terrorism."
"As for talk of a ceasefire, it comes from states that do not want an end to terrorism in Syria, but which want to shore up the positions of those terrorists."
She said Turkey was primarily responsible for the conflict and refugee crisis, because it "was the one that attacked Syria", and it was now seeking to gain from the issue by demanding membership of the European Union and financial incentives.
"The solution to the refugee crisis is via the return of security to Syria, and I am confident that the majority of Syrians dream of returning to their country," she said.
"What happened in Syria is a Turkish aggression, and therefore with all sincerity I say to the European and Western states that Turkey is the problem. The Erdogan government is the problem, and cannot be part of the solution."
(Editing by Peter Graff and Giles Elgood)