Experts are warning that stronger curbs must be considered for the housing market amid fears that London is starting to show "bubble-like conditions".
By 2018, the average house price in London is expected to reach nearly £600,000 - some 3.5 times the average price in Northern Ireland and more than 3.3 times the average in the North East, according to a report from economic forecasting group EY ITEM Club.
The report said that while the rest of the UK is returning to normality, London's housing market is showing signs of "bubble-like conditions" and policy makers should be prepared to step in.
It said the Bank of England's Financial Policy Committee (FPC), which oversees stability, may need to consider imposing a formal limit on income multiples in relation to the size of the mortgage that someone wants to borrow.
The report came as a separate paper from think tank Civitas suggested that restrictions should be placed on overseas investment in London homes to help ease "rampant house price inflation" and the problem of younger people and families being "priced out" of the market.
But Andrew Goodwin, senior economic advisor to the EY ITEM Club, said that calls to scrap or alter Help to Buy were a "red herring" and doing this could choke off the housing market recovery in the rest of the UK without tackling London's particular issues.
He said: "House prices across most of the country remain well below their pre-crisis peaks and there seems little danger of a bubble developing. But London, which is suffering from a combination of strong demand and a lack of supply, is increasingly giving us cause for concern."
The report said that income multiples are a "key measure in judging the sustainability of prices".
It said: "We think that caution on the part of mortgage borrowers and lenders will prevent this from moving above a factor of three, just as it did in the last expansion.
"However, were income multiples to rise further in London, or if other regions were to increase and pull the national average up towards three, it would warrant the FPC intervening to push multiples back down."
Recent Land Registry figures showed that house prices in London increased at more than double the rate of the rest of the UK over last year. London house prices leapt by 11.2% over 2013 to reach £403,792 on average, while prices across England and Wales generally lifted by 4.4% in the 12 months to December to reach £167,353.
London has continued to be a strong pull for wealthy investors looking for a "safe haven" to place their cash.
The EY ITEM Club report pointed to research showing that prices in prime central London now sit at 27% above their 2007 peak, with this market "being affected mainly by the level of interest from foreign investors".
Dean Hodcroft, head of EY's real estate, hospitality and construction team, said: "Bursting a bubble at the luxury end of the market, which continues to attract interest from international cash buyers with the seemingly irresistible global draw of London's X-factor, may prove tricky."
Meanwhile, the Civitas paper argued that non-UK residents should only be allowed to buy a property here if their investment will also boost the number of homes.
The idea reflects a system in Australia, where all non-residents wishing to purchase property must apply to that country's Foreign Investment Review Board (FIRB).
They are not allowed to buy an existing home but they may be allowed to buy an unoccupied new property - provided they can satisfy the FIRB that the housing stock has increased.
Civitas said that alongside Australia, similar controls on overseas investment are used by Switzerland, Denmark and Singapore to ensure that purchases are in the public interest.
The think tank proposes setting up a "non-resident housing investment agency" for the UK to which non-residents would need to apply for permission to buy.
Permission would not be granted unless the agency believed that a genuine increase in the housing stock would take place, thereby helping to ease the upward pressure on house prices.
The paper, co-written by director of Civitas David Green and director of communications at the body Daniel Bentley, said: "London property is now seen for many in terms of its investment potential, as a safe haven for cash in an unstable global economic climate, rather than something that should be meeting a basic social need for the capital's residents.
"For too many it is providing financial shelter rather than human shelter."
Housing Minister Kris Hopkins said: "With Help to Buy representing just 6% of overall sales in London it's important that we continue to offer this help to aspiring homeowners so they can get on the property ladder with a fraction of the deposit they would normally require, while developers have pledged to build more as a direct result of this scheme.
"The London housing market has received valuable support from foreign investment, unlocking development and leading to the building of homes that wouldn't otherwise happen.
"However, I welcome moves by the Home Builders Federation to ensure properties are marketed to UK buyers and those abroad, and for our part we've made changes to the tax rules to make sure overseas buyers pay their fair share."