BEIRUT: Syrian President Bashar Assad has denied ordering his troops to kill peaceful demonstrators, telling the U.S. television channel ABC that only a "crazy" leader kills his own people.

Assad is under mounting international pressure, including a threat of sanctions from the Arab League, over a crackdown on nationwide anti-government protests in which the United Nations says more than 4,000 people have been killed.

"We don't kill our people ... No government in the world kills its people, unless it's led by a crazy person," ABC's website Wednesday quoted Assad as saying in a recorded interview.

"Most of the people that have been killed are supporters of the government, not the vice versa," Assad said.

Syrian activists say around a quarter of the more than 4,500 deaths they have recorded in nine months of protest have been among the security forces. Most foreign media have been excluded from Syria, making it hard to verify events independently.

The Arab League has threatened to impose sanctions on Syria unless armed forces are verifiably withdrawn from towns and cities and a political dialogue is opened with opposition representatives. Major Western powers as well as neighbors Turkey and Jordan are calling on Assad to step down.

U.S. Secretary of State Hillary Clinton said on Tuesday that Washington and its NATO allies wanted Assad to make way for a government ready to establish the rule of law and protect "the rights of all citizens, regardless of sect or ethnicity or gender".

Peaceful protests against Assad, inspired by the Arab Spring in Tunisia and Egypt, were met with massive force as soon as they began in March. Now Syria is creeping closer to civil war as armed opposition groups organise and move into some city districts.

Assad conceded that some members of his armed forces had gone too far, but said they had been punished.

"Every 'brute reaction' was by an individual, not an institution, that's what you have to know," he told ABC's Barbara Walters.

"There is a difference between having a policy to crack down and between having some mistakes committed by some officials," he said. "There was no command to kill or be brutal."

Asked if he regretted the violence that has beset his country, he said he had done his best to "protect the people".

Assad repeated that he was introducing reforms and elections, but said the changes could not be rushed:

"We never said we are a democratic country ... we are moving forward in reforms, especially in the last nine months ... It takes a long time, it takes a lot of maturity to be a full-fledged democracy."

He said the mounting international effort to impose sanctions on Syria would have little effect.

"We've been under sanctions for the last 30, 35 years. It's not something new," Assad said.

"We're not isolated. You have people coming and going, you have trade, you have everything."

U.S. State Department spokesman Mark Toner was quoted in U.S. media as saying it was "ludicrous" that Assad was "attempting to hide behind a sort of shell game and claim he does not exercise authority in his own country".

Russia and Algeria both called for the Arab League peace plan, which Syria says it is considering, to be given time.

Russian Foreign Minister Sergei Lavrov noted that months of effort to secure agreement on a regional plan had now finally started a handover of power in Yemen.

"The same kind of patience, the same kind of responsibility need to be exercised in relation to the realization of the plan of the Arab League in Syria," he told reporters after attending a meeting in Lithuania of the Organization for Security and Cooperation in Europe (OSCE).

Algerian Foreign Minister Mourad Medelci told lawmakers in Paris that Syria was in a "pre-civil war situation".

"Today we are in a situation where we are putting pressure on the Syrian government and, on the other hand, talking to the opposition to create the conditions for dialogue," he said.

"Outside of this dialogue, this transition will not happen. We must give the maximum chance to this Arab initiative."

Syria's state news agency SANA said an "armed terrorist group" had shot dead an army pilot on Tuesday in front of his home in the city of Homs, scene of some of the worst violence.

On Tuesday, SANA had reported that Syrian border guards had blocked an attempt by about 35 "armed terrorists" to enter from Turkey.

It said some of those who came over the border were wounded and escaped back to Turkey where they were picked up in Turkish military vehicles, SANA said.

Relations between Syria and Turkey have disintegrated since Syria began using force to suppress the revolt. Turkey has said a buffer zone may be required on its 900-kilometers border with Syria if the violence causes a mass exodus of Syrians.