Libya told an Arab summit on Saturday that a UN arms embargo on the country must be lifted to help prevent the advance of Islamic State militants.
"I say to those who oppose or delay the arming of the Libyan army that you are giving an opportunity to Daesh terrorists to flourish in Libya and to spread beyond it," said Aqila Saleh, president of Libya's internationally-recognised parliament, using a derogatory Arabic term for Islamic State.
"And the neighbouring countries will be the first affected."
Saleh was speaking to a meeting of leaders of Arab League member states in the Egyptian city of Sharm El-Sheikh. The summit is expected to agree on the formation of a unified Arab military force to counter growing regional security threats.
The UN Security Council last year passed a resolution that tightened the international arms embargo on Libya. The issue is highly sensitive among Arab states.
Last year, Libyan Prime Minister Abdullah al-Thinni accused Qatar of sending military planes loaded with weapons to a Tripoli airport controlled by an armed opposition group. Doha denied the accusations.
Qatar helped bankroll rebels who ousted Muammar Gaddafi, and is an ally of Egypt's Muslim Brotherhood, an Islamist movement with a following in many Muslim countries including ties to the opposition group now controlling Tripoli.
The government has also accused Sudan of having tried to arm an Islamist-leaning group which has seized Tripoli and forced the elected parliament and officials to relocate to the east of the country.
Analysts say Libya is turning into a conflict zone for competing regional powers and faces the threat of civil war four years after Gaddafi's fall.
Egypt, which bombed Islamic State targets in Libya after the group beheaded 21 Egyptians in the North African country, has been pressing for the arms embargo to be lifted.
Cairo has accused Qatar of supporting terrorism, allegations it denies. Ties between the countries have been strained since the Egyptian army removed the Brotherhood from power in 2013.