By Saad Sayeed and Ariba Shahid

ISLAMABAD, April 9 (Reuters) - Pakistan is under huge pressure to pull off what some diplomats regard as mission impossible: broker a peace deal between Iran and the United States to stabilize the world economy while safeguarding delegates already arguing over a fragile truce.

Army chief Field Marshal Asim Munir and Prime Minister Shehbaz Sharif engaged in weeks of diplomacy to halt a war that could deepen instability along Pakistan's western border with Iran and Afghanistan, with which it has recently exchanged fire.

April 9 (Reuters) - U.N. Secretary-General Antonio Guterres' personal envoy Jean Arnault met Iran's Deputy Foreign Minister Majid Takht-Ravanchi in Tehran on Thursday as part of U.N. efforts to bring about an end to the Iran war, the U.N. said.

Arnault also met representatives of the Iranian Red Crescent and visited some civilian sites damaged in recent air strikes, including a university and an apartment block that had been destroyed, U.N. spokesperson Stephane Dujarric told a regular briefing in New York.

By Patricia Zengerle and Richard Cowan

WASHINGTON, April 9 (Reuters) - U.S. House of Representatives Republicans on Thursday blocked a Democratic effort to end U.S. attacks on Iran, as Donald Trump's party continued to prevent efforts to rein in the Republican president's war powers.

Representative Chris Smith, a New Jersey Republican, presided over an abbreviated "pro forma" House session, ending it before a group of Democrats could seek to pass the resolution via unanimous consent.

Thousands of Iranians rallied Thursday in a tribute to former supreme leader Ali Khamenei, killed on the first day of the war with the United States and Israel, expressing criticism of talks expected in Pakistan this week.

Holding portraits of their deceased leader and waving the national flags of the Islamic republic, supporters of Khamenei took part in rallies across the country after he died in the US-Israeli attack on February 28.

The 40-day mourning period following a death is an important rite of passage for Muslims.

BEIRUT, April 9 (Reuters) - Lebanon has spent the last 24 hours advocating for a temporary ceasefire to allow for broader talks with Israel, a senior Lebanese official told Reuters, saying it would be a "separate track but the same model" as a fragile truce brokered by Pakistan between the U.S. and Iran.

The official said no date or location had been set yet but Lebanon needed the U.S. as a mediator and guarantor of any agreement.

April 9 (Reuters) - Dozens of states issued a joint statement at the United Nations on Thursday condemning "unacceptable aggressive behavior" toward U.N. peacekeepers in Lebanon and calling for increased protections after the deaths there of three Indonesian soldiers.

The 63 countries and the European Union also expressed "deep concern over the humanitarian situation in Lebanon, especially the significant civilian casualties, the extensive destruction of civilian infrastructure and the mass displacement of more than one million people."

JERUSALEM, April 9 (Reuters) - Israeli Prime Minister Benjamin Netanyahu said on Thursday that he has given an instruction for Israel to begin peace talks with Lebanon that would also include the disarming of Hezbollah.

"In light of Lebanon's repeated requests to open direct negotiations with Israel, I instructed the cabinet yesterday to start direct negotiations with Lebanon as soon as possible," Netanyahu said in a statement. "The negotiations will focus on disarming Hezbollah and establishing peaceful relations between Israel and Lebanon."

By Nidal al-Mughrabi and Ali Sawafta

CAIRO/TAYASIR, West Bank, April 9 (Reuters) - Israel has approved the establishment of dozens of new Jewish settlements in the West Bank, an Israeli watchdog group said on Thursday, amid a rise in settler attacks on Palestinians across the occupied territory.

Prime Minister Benjamin Netanyahu's government has not formally announced the establishment of the 34 new settlements, many of them outposts in far-flung areas of the mountainous territory, the Peace Now watchdog group said in a statement.

LONDON, April 9 (Reuters) - Imposing a toll on ships sailing through the critical Strait of Hormuz would "set a dangerous precedent" and countries should not impede freedom of navigation, the UN's shipping agency said on Thursday.

Iranian officials have raised the idea of charging a toll for using the Strait after a two-week ceasefire between the United States and Tehran was agreed this week.

By Stine Jacobsen

COPENHAGEN, April 9 (Reuters) - Greenland's Prime Minister Jens-Frederik Nielsen said on Thursday that he represents a proud nation seeking to maintain global order, pushing back against the latest comments about the Arctic island by U.S. President Donald Trump.

Trump on Wednesday vented his frustration with NATO as relations reached a crisis point over the Iran war, stating that the military alliance was not around when needed, and that he still remembered Greenland, a "BIG, POORLY RUN, PIECE OF ICE".