German Foreign Minister Frank-Walter Steinmeier said Wednesday he backed Iranian involvement in a conference in Switzerland this month on ending the brutal nearly three-year-old war in Syria.

"My position is that we should try to include the neighbors -- Iran too," he said after talks in Berlin with his Swedish counterpart Carl Bildt.

Iranian Foreign Minister Mohammad Javad Zarif said Wednesday he was optimistic about a landmark nuclear agreement with world powers, saying negotiations were progressing amid "strong political will".

The comments by Iran's top nuclear negotiator on his Facebook page came on the eve of the resumption in Geneva on Thursday of talks aimed at putting into action the interim nuclear deal clinched in November.

The United States on Tuesday accused Iran of helping "brutalize" Syria as Secretary of State John Kerry prepared to talk to Russia about Tehran's potential role at a peace conference.

Kerry will meet in Paris on January 13 with Russian Foreign Minister Sergei Lavrov to discuss whether Iran should take part in the conference later this month in Switzerland aimed at ending the nearly three-year-old war in Syria, the State Department said.

Iran's President Hassan Rouhani defended Tuesday a landmark nuclear deal with world powers that promises modest sanctions relief, saying his government did not fear "the few" domestic critics.

Rouhani's defense came after repeated criticism by hardliners in parliament and the powerful Revolutionary Guards of the deal clinched in November that also requires Iran to curb temporarily parts of its nuclear drive.

A delegation of British lawmakers led by former foreign minister Jack Straw arrived in Tehran Tuesday amid moves by Iran and Britain to restore diplomatic ties, Iranian media reported.

The visit by the four MPs comes two months after Britain and Iran named non-resident envoys to re-establish ties severed in 2011 after hardline Islamists ransacked the British embassy compound in Tehran.

In Iran, free condoms and government-backed vasectomies are out, replaced by sermons praising larger families and discussions of even offering gold coins to the families of newborns.

Having successfully curbed birth rates for two decades, Iran now is promoting a baby boom to help make up for its graying population. But experts say it is difficult to encourage Iranians to have more children in a mismanaged economy hit by Western sanctions and 36 percent inflation.

The United States is open to "helpful" Iranian input during an upcoming peace conference in Switzerland aimed at ending Syria's war, U.S. Secretary of State John Kerry said on Sunday.

"We're happy to have Iran be helpful," he told reporters in Jerusalem.

Politically paralyzed by deep divisions exacerbated by the war in neighboring Syria, Lebanon is likely to see a continuing cycle of political violence, analysts say.

On Thursday, four people were killed and dozens others wounded in a bomb blast in the Beirut southern suburb of Haret Hreik, a stronghold of Hizbullah, less than a week after the assassination of former finance minister Mohammed Shatah, a member of the March 14 coalition.

Bahrain accused Iran's Revolutionary Guards Friday of providing opposition militants with explosives training in order to carry out attacks in the Gulf kingdom, announcing that it had arrested five suspects.

Bahrain is ruled by a Sunni Muslim dynasty but has a population that is majority Shiite. The government crushed a mostly Shiite-led uprising in 2011 and has long accused predominantly Shiite Iran of meddling in its affairs.

U.S. officials believe Hizbullah is smuggling advanced guided-missile systems into Lebanon from Syria piece by piece, the Wall Street Journal reported.

Some components of a powerful anti-ship missile system have already been moved to Lebanon within the past year, including supersonic Yakhont rockets, according to previously undisclosed intelligence.