Ethiopian security agents have seized hundreds of weapons smuggled through the porousEthiopia-Sudan border.

Ethiopian federal police communication head Fekadu Berhe said agents had seized nearly 500 light weapons and 13,000 bullets in the northern Ethiopia town of Metema.

Metema borders the Blue Nile region of Sudan.

On Saturday, an unspecified number of Ethiopian nationals who were allegedly involved in the smuggling were arrested.

The seizure comes just a month after six exiled and ethnic-based Ethiopian opposition groups announced the formation of armed movements against the government.

One, the Ethiopian Alliance for a Democratic Change (EADC), has openly declared its plan to attack strategic military targets and overthrow the government.

EADC is the newest armed opposition group against the Ethiopian government.

Most such opposition movements are based in neighbouring Eritrea, which maintains frosty relations with Ethiopia.

After the death of Ethiopian prime minister Meles Zenawi in August, exiled opposition groups have intensified their activities.

So far, at least 12 armed rebel groups have sought to bear arms against the powerful Addis Ababa government, seen as authoritarian.

Last month, the prominent opposition group Ogaden National Liberation Front (ONLF) started negotiations with the Ethiopian government under Kenyan mediation.