The United States stepped into Scotland's knife-edge independence debate on Monday, indicating that it hoped that its "special relationship" ally Britain would remain "united."

White House spokesman Josh Earnest stressed that Washington respected the right of Scots to decide their future in Thursday's referendum but hoped for a "strong, robust and united" partner.

The campaign for Scotland to stay in the United Kingdom has taken the lead, a new opinion poll showed Saturday, after a shock survey last weekend put the pro-independence camp ahead.

The Survation poll commissioned by the "Better Together" pro-union campaign gave them 47 percent support against 40.8 percent for the nationalists, with nine percent undecided and 3.2 percent refusing to say.

Germany's foreign minister said Thursday he would prefer to see Britain remain united after Scotland's independence vote but said it wasn't for him to wade into Britain's domestic matters.

Frank-Walter Steinmeier was asked about the historic referendum to be held in Scotland on September 18 at a joint press conference with his British counterpart Philip Hammond.

Britain won't join the United States in air strikes against Islamic State jihadist fighters in Syria, Foreign Secretary Philip Hammond said Thursday, without ruling out similar action in Iraq.

"Let me be clear Britain will not be taking part in any air strikes in Syria," he said in Berlin.

Iran and world powers have a "difficult road" ahead as they attempt to agree a nuclear deal by a November deadline, with major differences remaining, Tehran's lead negotiator said Thursday.

"We are always optimistic. But we have a difficult road to go," Abbas Araqchi told reporters after a day of talks in Vienna with officials from France, Germany and Britain.

Britain is to ship heavy machine guns to Kurdish forces fighting Islamic State jihadists in Iraq, Defense Secretary Michael Fallon announced Tuesday.

The arms shipment, worth £1.6 million ($2.6 million, two million euros), will arrive in Iraq on Wednesday.

London's Luton airport was evacuated on Monday, all incoming flights canceled and the main approach road closed off after a "suspicious item" was found during security checks, officials said.

A spokeswoman from the airport, the fifth largest in Britain, told Agence France-Presse the evacuation of the main terminal building was sparked by the discovery of a "suspicious item found in the security search area."

A man appeared in court Saturday charged with the murder of an 82-year-old woman reportedly found beheaded with a machete in her suburban London garden.

Palmira Silva, a grandmother who still worked at her family's cafe, was attacked in her garden in Edmonton, north London, on Thursday.

A woman was found beheaded on Thursday in a back garden in north London, according to British media reports, but police said the attack was not linked to terrorism.

Police discovered the body in the suburb of Edmonton after being alerted at midday by local residents who said a man with a knife was attacking a cat or dog.

Scotland's prospects of independence after a referendum in two weeks' time received a boost Tuesday when a second opinion poll showed the "Yes" camp within touching distance of victory.

While all the polls have put the "No" camp ahead, the latest YouGov survey was the second in four days to suggest that the gap is closing ahead of the September 18 vote.