African Union troops alongside Somali forces seized the formerly Islamist-held town of Wanla Weyn on Sunday, the latest loss for the Al-Qaeda-linked Shebab fighters, commanders said.
Its capture -- reportedly without a fight -- is a key step towards opening up the main highway linking the capital Mogadishu to Baidoa, a major town wrested from the Shebab by Ethiopian troops in February.
The AU mission in Somalia (AMISOM), which also seized the Balli Doogle airstrip on Sunday, have now advanced over 90 kilometres (55 miles) northwest from Mogadishu since launching an offensive outside the city in May.
"Somali government forces with the support of AMISOM troops have secured the strategic town of Wanla Weyn on the Afgoye to Baidoa corridor," said Andrew Gutti, commander of the 17,000-strong AMISOM force.
Wanla Weyn lies roughly a third of the way to Baidoa from Mogadishu, with the remaining 160 kilometres (100 miles) still controlled by the Shebab.
"The capture of this town denies Al Shebab another source of illegal income after a string of defeats," Gutti added in a statement.
"It will also facilitate the provision of much needed humanitarian assistance to the local population."
Kenyan troops -- who invaded Somalia a year ago before later integrating into AMISOM -- are also pushing up from the south, having last week seized the Shebab bastion and major port of Kismayo.
The hardline insurgents still control the town of Jowhar, some 80 kilometres (50 miles) northeast of Mogadishu, and the small port town of Barawe, lying some 180 kilometres (110 miles) down the coast from the capital.
However, the fighters have largely retreated ahead of each assault, with some reportedly relocating to the northern Galgala mountains in Somalia's semi-autonomous Puntland region.
In addition, vast and remote areas of bush surround many of the towns seized, which could also provide a haven for fighters who have fled.
The extremists, who left fixed positions in the capital last year, have also switched to guerrilla attacks in many areas, including the use of suicide bombers.