Witnesses in Somalia say columns of Ethiopian troops have crossed into the country and are marching toward key al-Shabab strongholds, apparently opening a new military front against the Islamist militant group.

A government official, who wished to remain anonymous, confirmed the reports to VOA on Monday, saying the soldiers had reached the town of Luq in the southwest Gedo region.

The location includes a major road leading to the Bay and Bakool regions, which are under al-Shabab's control.

The official says the Ethiopian convoy entered Somalia through the border town of Dolow.

Al-Shabab is facing pressure inside Somalia from Ethiopian forces already there, Kenyan troops who entered the country in October, and African Union troops in the capital, Mogadishu.

Last week, the al-Qaida-linked group said it killed 33 Ethiopian soldiers during a suicide attack on an army base in the town of Beledweyne. The Ethiopian military typically does not release casualty figures.

Al-Shabab is fighting to overthrow Somalia's U.N.-backed transitional government and impose strict Islamic law. The group controls large sections of southern and central Somalia but has lost ground in recent months. AU and Somali troops drove the group out of Mogadishu last year, while Ethiopian forces recently took control of Beledweyne.