Somali and African Union forces have launched a long-awaited fresh offensive against al-Shabab fighters aimed at capturing remaining ports from the armed group, army and government officials have said.
"Operation Indian Ocean started late last night ... the enemy is fleeing and the forces are making successful advances so far," said Abdukadir Mohamed Nur, the governor of southern Somalia's Lower Shabelle region.
Witnesses reported hearing the booms of heavy shelling, as well as seeing convoys of tanks and armoured vehicles heading towards the al-Shabab stronghold of Bulomarer, about 160km southwest of the capital Mogadishu.
Al Jazeera's Hamza Mohamed reported that the town of Bulomarer was successfully recaptured by the AU mission in Somalia (AMISOM) and Somali government troops, after an intense gunbattle earlier in the day.
Two AU soldiers were injured and brought back to Mogadishu, while there were also reports of casualties on the al-Shabab side, he said.
Our reporter said that the AMISOM troops were headed toward the town of Kurtunwarey, which is between Bulomarer and Barawe, the last major port held by the armed group.
'Operation Indian Ocean'
The al-Qaeda-linked al-Shabab are still a powerful and dangerous force but have lost a string of towns to the 22,000-strong AMISOM.
Al Jazeera's Mohammed Adow, reporting from Mogadishu, said: "This offensive is called Operation Indian Ocean. It is about denying al-Shabab any access to the sea to stop the group from bringing in arms."
The southern port of Barawe is now one of the few major settlements under their control, and is vital to al-Shabab finances, as the main hub of a multi-million dollar charcoal trade.
Al-Shabab are fighting to topple Somalia's internationally-backed government, and regularly launch attacks against state targets, as well as in neighbouring countries that contribute to the AU force.
The fighting comes as UN and aid workers warn large areas of Somalia are struggling with dire hunger and drought, three years after famine killed more than a quarter of a million people.
In January 2013, French commandos carried out a botched raid on Bulomarer in a bid to free a secret agent held hostage. The bid failed and resulted in the death of two French soldiers and the hostage.