NAIROBI, Kenya -- Kenya's foreign minister summoned Eritrea's ambassador on Friday and "raised concern" over the possibility that planes from Eritrea are supplying weapons to Somali militants whom Kenyan forces are battling in southern Somalia.

Moses Wetangula said if that is the case, Kenya has "a series of options" to deal with the situation. He did not say what those options include.

have and information available that there is a possibility that arms supplies are flowing from his country to al-Shabab," Wetangula said.

"Make no mistake, Kenya will do everything possible to make sure, one, that if it's in our capacity, supplies to al-Shabab must be stopped," he said.

Eritrea denied this week that it is arming fighters in Somalia, and Eritrea's foreign minister is expected in Kenya shortly.

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Kenya has said it believes three planes flew into southern Somalia over the last week with weapons meant for al-Shabab fighters. The military spokesman said Thursday that the military would shoot down or bomb on the ground any unidentified planes it believes to be supplying the Al Qaeda-linked militants.

A July report by the U.N.'s Monitoring Group on Somalia and Eritrea said that al-Shabab controls two large airports and one former military airport with asphalt runways. The report also said that illicit flights with weapons or fighters for Somali militants could be originating from Eritrea, Yemen or the United Arab Emirates.

The U.N. report said Eritrea consistently denies providing military support to armed groups in Somalia, but that "new information ... not only confirms many previous allegations of Eritrean military involvement, but also offers firm grounds to believe that Eritrea still retains active linkages to Somali armed groups."

Hundreds of Kenyan troops moved into southern Somalia last month after a spate of kidnappings by armed Somalis, though officials said the military incursion had been planned for months.

Militants now face fighting on two fronts -- from Kenyan forces in the south, and from Ugandan and Burundian troops in the Somali capital.

Al-Shabab has threatened to launch terrorist attacks in Nairobi in retaliation for the attacks by Kenyan troops.

Meanwhile, officials on Kenya's coast indicated that Kenya's Navy shot and killed seven men at sea, though three survived the attack. Relatives said the boat was full of innocent fishermen, though officials said they were treating the surviving men as possible insurgents.

A relative of one of the fishermen on the targeted boat, Said Abdulrahman, said the boat was attacked despite the fact the fishermen had alerted authorities of their whereabouts.

A local government official, Richard Karani, said he was aware of the incident. He said three people from the boat had been arrested and the whereabouts of the other seven were still unknown.

Kenyan military spokesman Maj. Emmanuel Chirchir said he was gathering information on the incident and couldn't yet comment.