"The world issues affect our financial markets. Most of our fixed rate money comes from international money markets like the States," he said.
Mr Rapson said the changes could affect home buyers.
"If you have bought a $600,000 home with a $120,000 deposit. That's a $480,000 mortgage, if there was a 30 point increase, that is $1040 a year and then tax on top of that.
"For the young folk, that's a problem. You always stretch yourself when you buy your first home. Eighty per cent of people who do borrow for a first home, do extend themselves a bit. They just don't understand the implications of what that fixed commitment means."
Craigs Investment Partners head of private wealth research Mark Lister said mortgage rates would go up regardless of what the OCR did.
Mr Lister said the interest rates were the lowest they had been in decades.
"They are exceptionally low, it shouldn't be a surprise to people they would go up. Things don't stay at rock bottom forever."
Tauranga Harcourts franchise general manager Nigel Martin said when the OCR dropped it did affect the floating mortgage rates initially.
But most of the changes and increases in the interest world had already been factored into the current mortgage rates already offered by banks, he said.
"I don't know if we will see a huge difference in our market place at this stage."
Mr Martin predicted any jump in interest rates would be about half a per cent.
November and December were often very busy times in the property market, he said.
Ross Stanway, chief executive of Eves and Bayleys Real Estate, said it was too early to tell if anything would happen.
Interest rates had been down at very low levels for a very long time, he said.
"If they do go up, it's a question of if, when and by how much. Those are the things we don't know yet."
Why interest rates are likely to go up
On August 15 the five year swap rate, the rates at which bank's borrow on the money market, was 2.08 per cent while on Monday last week it was 2.42 per cent, he said.
The three-year swap rate had risen from 1.98 per cent to 2.23 per cent over the same time.