Tempers heat up as Scotland nears referendum on independence

With insults, egg-throwing and rage, the campaign ahead of Scotland's independence referendum is heating up, even forcing intervention by British Prime Minister David Cameron.

"There's nothing wrong with a bit of heckling but throwing things isn't necessarily part of the democratic process," Cameron said on Friday, after a "No" campaigner was pelted with eggs.

"I've always thought that it isn't right to throw eggs at people. I had one myself in Cornwall once, it's an interesting experience," he said.

The victim of the egg attack was Jim Murphy, an ex-Europe minister and formerly the Scotland secretary in the British government.

Murphy said on Friday he was suspending his grass-roots tour, accusing the "Yes" campaign of employing intimidation tactics. Pro-independence leader Alex Salmond also condemned the incident but said he, too, had been a victim of harassment.

"All politicians should beware, yes of course we call for good conduct, online and offline, yes of course we do," said Salmond, Scotland's first minister and Scottish National Party leader.