UPDATE 1-Iran says sanctions to fail, repeats Hormuz threat

* Iran politicians say EU ban won't hurt, may be reversed

* Say Iran has plenty of time to find export options

* Tehran summons EU ambassador over "illogical decision"

By Mitra Amiri

TEHRAN, Jan 24 (Reuters) - Iranian politicians said on Tuesday they expected the European Union to backtrack on its oil embargo and repeated a threat to close the vital Strait of Hormuz shipping lane if the West succeeds in preventing Tehran from exporting crude.

A day after the EU slapped a ban on Iranian oil, Iran's tone appeared defiant, even sceptical, with Tehran insisting that, with the EU faced with its own economic crisis, it needs Iran's oil more than Iran needs its business.

The ban is expected to take full effect within six months.

"The West's ineffective sanctions against the Islamic state are not a threat to us. They are opportunities and have already brought lots of benefits to the country," Intelligence Minister Heydar Moslehi told the official IRNA news agency.

Speaking in London, Saudi Arabia's ambassador to Britain Prince Mohammad Bin Nawaf said the region was witnessing "a very difficult and a very tense situation".