A Kenyan military spokesman has sent out this warning on Twitter: Do not sell donkeys to Somali militant group al-Shabab.

Major Emmanuel Chirchir has been using the social networking site to communicate with the public as Kenya's military battles the al-Qaida-linked militant group on Somali soil.

Chirchir tweeted on Thursday that al-Shabab militants have “resorted to using donkeys to transport their weapons.”

The military spokesman asked Kenyan and Somali civilians not to sell donkeys to the group. He warned that any “large concentration and movement of loaded donkeys will be considered an al-Shabab activity.”

Earlier this week, Chirchir said Kenyan troops are poised to sweep across 10 towns in southern Somalia in pursuit of al-Shabab. The militant group has summoned reinforcements from other parts of the country.

Chirchir also posted a video link on his Twitter page that allegedly shows the Kenyan Navy sinking a vessel with 18 al-Shabab fighters.

The spokesman says all the militants were killed in the attack. The video seen on the link shows black smoke billowing up from a burning vessel. It's authenticity could not be confirmed.

The Kenyan military launched its offensive in Somali three weeks ago. The government has accused al-Shabab militants of crossing into Kenyan territory from the Somali border and kidnapping several foreigners.

Al-Shabab has been fighting since 2008 to topple the Somali government. The group was recently left the capital, Mogadishu, but still controls large sections of southern and central Somalia.