Updated 10:42 p.m. ET
(CBS/AP) BAGHDAD - Rebels attacked Syrian forces Thursday along the nation's porous border with Iraq, killing at least 21 soldiers and seizing control of all four major border posts, a senior Iraqi army official said.
Additionally, rebels took control of two major crossings on the border with Turkey, Reuters reports. Syrian rebel spokesmen said they seized control of the customs and immigration buildings on the Syrian side of the northern Turkish frontier gate of Bab al-Hawa, as well as the Jarablus crossing.
Near the Iraq border, the assaults against Syria's government unfolded throughout the day, putting the Iraqi army on high alert to prevent any violence from spilling across the border.
Iraq's Deputy Interior Minister Adnan al-Assadi told Agence France Presse Iraqi border guards had witnessed the Free Syrian Army take control of a border outpost, detain a Syrian army lieutenant colonel, and then cut off his arms and legs.
"Then they executed 22 Syrian soldiers in front of the eyes of Iraqi soldiers," Assadi said.
The situation has put the government of Iraq on high alert.
"We have security concerns because the border crossing now is out of the Syria government's control, and nobody can anticipate what will happen," said Iraqi Army Brig. General Qassim al-Dulaimi.
Al-Duliami said about a half-dozen rebels stormed the Syrian border crossing near the Iraqi town of Qaim on Thursday morning. He said the rebels forced the border guards from their posts but did not cross into Iraq.
Qaim is located about 200 miles west of Baghdad. Mohammed Fathi, spokesman for the governor of Iraq's western Anbar province that includes Qaim, said the border crossing had already been closed to traffic because of the civil war.
Hours later, in the remote Sinjar mountain range, al-Dulaimi said rebels attacked a Syrian army outpost near the Iraqi border, killed 20 soldiers and their commander. The rebels then seized control of the outpost, al-Duliami said.
As a result of the attacks, the Iraqi government is sending extra troops to the border, reports the New York Times.
"We will not accept either the Syrian army or the Free Syrian Army to enter our territory," Col. Dhia al-Wakil, a spokesman for the Baghdad Operations Command, said on local television, according to the Times.
The leadership in Iraq has long cast a weary eye at the uprising in Syria, fearing it could spill across their border, which is 363 mile long.