Iranian state television on Monday showed several Iranians alleged to be part of a group of 13 who "confessed" to killing four Iranian nuclear scientists after being trained by Israeli intelligence.

It said the network received orders from "Washington and London."

Iran "strongly" denies that 48 of its citizens taken hostage in Syria at the weekend are Revolutionary Guards, as claimed by their rebel captors, according to the state television website on Monday.

"We strongly reject the claims of some media that the kidnapped pilgrims are members of Iran's Revolutionary Guards," Amir Abdollahian, a deputy foreign minister in charge of Arab affairs, was quoted by the IRIB broadcaster as telling Iran's al-Alam Arabic-language network.

Syrian regime forces shelled several areas of the northern city of Aleppo on Monday morning, and shooting was also reported in other neighborhoods of the embattled commercial capital, monitors said.

Clashes in the rebel-held district of Salaheddin killed a rebel commander, the Britain-based Syrian Observatory for Human Rights said.

Five gunmen who slew 16 Egyptian guards near the border with Israel before crossing into the Jewish state in an armored vehicle have been killed, an army spokesman said Monday.

"The bodies of the five gunmen have been found by the Israeli army," said the spokesman a day after the incident but did not give details.

Three prominent U.S. senators called late Sunday for direct U.S. military aid to Syrian rebels, including use of air power to protect rebel-controlled areas in the country.

The senators -- John McCain, Joseph Lieberman and Lindsey Graham - said in an op-ed piece in The Washington Post they were aware of the risks associated with deepening U.S. involvement in the conflict in Syria.

Gunmen in two armored vehicles crossed into Israel from Egypt near the Kerem Shalom crossing on Sunday after hijacking the vehicles from an Egyptian outpost where they had killed at least 13 troops, the Israeli military said.

One vehicle exploded by itself while the other was destroyed from the air, the Israeli military added.

Three Syrian intelligence officers have defected from the Damascus regime and sought refuge in neighboring Jordan, a spokesman for the rebel Free Syrian Army said on Sunday.

"Colonel Yaarab al-Sharaa, his brother Mohammed Kanaan al-Sharaa and Colonel Yasser Ali Hajj, who worked in political intelligence in Damascus, have defected and are in Jordan," Kassem Saadeddine told Agence France Presse.

Turkey's interior minister said Sunday some 115 Kurdish rebels have been killed in a large-scale military offensive launched in the southeast of the country in July.

"We reached the conclusion that 115 members of the separatist terrorist organization have been rendered ineffective" since an offensive launched on July 23 to 24, Idris Naim Sahin was quoted as saying by the Anatolia news agency, referring to members of the outlawed Kurdistan Workers' Party (PKK).

A British photographer who was held hostage in Syria for a week said on Sunday that his captors were international jihadists who included several Britons.

Freelance photographer John Cantile and his Dutch colleague Jeroen Oerlemans were kidnapped in northern Syria on July 19 and freed a week later.

Attacks mainly targeting Iraqi security forces killed four people, among them three policemen, and wounded nine on Sunday, security and medical officials said.

So far this month attacks have killed 54 people, 41 of them members of the security forces, according to an Agence France Presse tally based on security and medical sources.