Pakistan's defence minister has threatened to retaliate in kind to any Israeli nuclear strike after apparently being tricked by a fake news site into a confrontation on social media.

Khawaja Asif was responding to an invented story published on the website AWDNews and headlined: "Israeli Defense Minister: If Pakistan send ground troops into Syria on any pretext, we will destroy this country with a nuclear attack."

"Israeli def min threatens nuclear retaliation presuming pak role in Syria against Daesh (Islamic State).Israel forgets Pakistan is a Nuclear state too" the Pakistani minister tweeted Friday.

His missive prompted a clarification from Israel's Ministry of Defense, which responded to him on Saturday:

"@KhawajaMAsif The statement attributed to fmr Def Min Yaalon re Pakistan was never said," adding: "KhawajaMAsif reports referred to by the Pakistani Def Min are entirely false".

Israel has a policy of ambiguity in relation to its nuclear arsenal, neither confirming nor denying its existence, but is widely believed to be an atomic power.

Pakistan, which conducted its first nuclear test in 1998, is believed by analysts to have around 120 nuclear weapons and the fastest growing stockpile.

Mainly Muslim Pakistan has no diplomatic ties with Israel.

Asif was widely mocked for his blunder.

"Our nuclear program is too serious a business to be left to Twitter-addicted politicians", said prominent TV journalist Nusrat Javeed.

There is a rising tide of fake articles being widely shared on social media.

Earlier this month a rifle-wielding man entered a pizza restaurant in Washington, saying he wanted to investigate a fake news story that the establishment was a centre for child abduction linked to failed US presidential candidate Hillary Clinton.

Last week Google said it was working to refine its algorithm to weed out "non-authoritative" information after a British news report showed a Holocaust denial website was the top result when users asked "Did the Holocaust happen?"