UNITED NATIONS (Reuters) - The United Nations Security Council unanimously voted to renew the mandate for a peacekeeping mission in Lebanon on Wednesday, following tense negotiations amid U.S. and Israeli criticism that U.N. troops should do more to stop Hezbollah gaining arms.

U.S. Ambassador to the United Nations Nikki Haley delivers remarks during a meeting by the United Nations Security Council at the U.N. headquarters in New York City, U.S., August 29, 2017. REUTERS/Andrew Kelly

The U.N. Interim Force in Lebanon (UNIFIL) - established in 1978 - patrols Lebanon’s southern border with Israel. Washington regards Hezbollah, which supports the Syrian government and has a strong presence in south Lebanon, as a terrorist organization.

U.S. Ambassador to the United Nations Nikki Haley said Washington wanted the French-drafted resolution to renew UNIFIL’s mandate to “ensure UNIFIL is doing its job to the fullest extent possible.”

After a 2006 war between Israel and Hezbollah, the UNIFIL mandate was expanded to task peacekeepers with making sure southern Lebanon was “free of any armed personnel, assets and weapons” other than those belonging to the Lebanese government.

“For too long UNIFIL’s leadership has failed to make sure this goal is realized,” Haley told the council after the vote.

The mission mandate has not changed, but the resolution adopted on Wednesday spells out that peacekeeping operation is authorized to “take all necessary action in areas of deployment of its forces ... to ensure that its area of operations is not utilized for hostile activities.”

The resolution also asks U.N. Secretary-General Antonio Guterres to look at ways the peacekeeping mission can increase its visible presence, including through patrols and inspections.

“At the direction of its patron, Iran, the terrorist organization Hezbollah is stockpiling an offensive arsenal in southern Lebanon,” Haley told the 15-member council after the vote. “It is preparing for war.”

“They have thousands of missiles and thousands of trained fighters all beyond the control of the Lebanese government. It is apparent to everyone who cares to see it,” she said.

Hezbollah defends its possession of weapons as necessary to defend Lebanon, but does not say where they are.

Deputy French U.N. Ambassador Anne Gueguen described the negotiations on the resolution as “difficult.”

“UNIFIL, of course, can do better and can do more, but no-one in this council can imagine for one second the environment existing there without UNIFIL,” she told the council.

Israel has regularly complained that UNIFIL has too soft an approach toward enforcing the 2006 ceasefire and would like to see stronger action against Hezbollah military deployment that Israel alleges is taking place in violation of the ceasefire.

Lebanon also accuses Israel of violating the ceasefire by sending warplanes into its airspace.