'Saudi weapons' seen at Syria rebel base
BBC News has uncovered evidence that appears to suggest that weapons intended for the Saudi military have been diverted to Syrian rebels.
Three crates from an arms manufacturer - addressed to Saudi Arabia - have been seen in a base being used by rebel fighters in the city of Aleppo.
How the small crates reached Aleppo is unknown, and the BBC was not allowed to film their contents.
Saudi Arabia has refused to comment on the matter.
Turkey is calling for "international action" on Syria after a sixth consecutive day of cross-border shelling.
Turkey returned fire across the border on Monday after a Syrian shell fell on its territory.
Turkey would continue to do everything necessary to protect its borders, President Abdullah Gul said on Monday, adding that the "worst-case scenarios" were now taking place in Syria.
No-one was hurt in the latest incident, near the town of Altinozu, in Hatay province, the Turkish semi-official Anatolia news agency reported.
Last week, a Syrian shell killed five Turkish civilians in the border town of Akcakale.
Meanwhile, fighting has intensified around the central Syrian city of Homs.
Syrian troops launched an assault on Homs, advancing into a rebel-held district after four days of bombardment.
"The army is in the midst of trying to cleanse the last rebel districts of the city of Homs," a Syrian army commander told the Associated Press news agency.
The crates of ammunition found in an Aleppo mosque were made by the Ukrainian firm Dastan, which specialises in naval weapons and missile complexes.
What was in the crates is unknown, says the BBC's Ian Pannell, who has been in Aleppo, as is how they ended up there.
But their presence clearly suggests that someone in the Gulf is actively helping the rebels fighting to overthrow President Bashar al-Assad, our correspondent says.
When contacted by the BBC, Saudi officials refused to comment.
The BBC's security correspondent Frank Gardner says Saudi Arabia generally prefers to conduct its foreign affairs through low-key, behind-the-scenes discretion.
The apparent discovery of Saudi ammunition in a Syrian mosque could attract unwelcome attention, he adds.
Privately, opposition sources have confirmed to the BBC that they are receiving assistance from Saudi Arabia and Qatar.
The New York Times reports that Saudi and Qatari officials are sending small arms to the rebels, but are holding off sending heavier equipment, such as shoulder-fired missiles.
This is in part because they have been discouraged by the United States, which fears the heavier weapons could end up in the hands of terrorists, the newspaper says.
Meanwhile, in a speech on foreign policy on Monday, US presidential candidate Mitt Romney has said that if elected, he would back Western-friendly elements among the Syrian rebels.
Extracts of his speech released by his campaign include the following pledge on Syria: "I will work with our partners to identify and organize those members of the opposition who share our values and ensure they obtain the arms they need to defeat Assad's tanks, helicopters, and fighter jets."
The UN has warned of rising tensions and has urged those supplying weapons to both sides to stop doing so.
UN Secretary General Ban Ki-moon said tensions were increasing in the region, adding that he was "deeply concerned" by the continued flow of arms to both sides, despite international embargoes.
"I urge again those countries providing arms to stop doing so. Militarisation only aggravates the situation," he told the World Forum for Democracy, in the French city of Strasbourg.
Syria is not on the agenda at this week's meeting of Nato foreign ministers, but in an interview with the BBC, Secretary General Anders Fogh Rasmussen said Turkey - a Nato member - could count on solidarity.
Nato had no intention of interfering militarily in Syria, he said, but plans were in place to protect and defend Turkey if necessary.