Plans to hike stamp duty costs for buy-to-let landlords and second home buyers could push up both house prices and rents, experts have warned.

The Government's plans could "turbo-charge" the housing market in the coming months and spark a rush of people snapping up properties before the changes come into force. This would push up competition for homes and therefore prices, it was argued.

Meanwhile, in the longer term, the moves could also discourage people from investing in a buy-to-let home - potentially restricting the supply of rental properties and increasing prices for tenants.

The Government unveiled a package of measures designed to boost people's home ownership prospects.

The Chancellor's measures promise to be the biggest affordable housebuilding programme since the 1970s, with more than 400,000 new homes set to be built across England.

Included in these announcements is a pledge that money raised from the tax on people buying their second home will be used to help those struggling to buy their first home. From April 1 2016, people buying additional properties, such as buy-to-let properties and second homes, will pay an extra three percentage points above current stamp duty rates.

The Government plans to use some of the extra tax collected to help communities where the impact of second homes is particularly acute.

The move comes on top of an announcement in the summer Budget that landlords will see their tax breaks restricted.

It was previously announced that f rom April 2016, a ''wear and tear allowance'', which allows landlords to reduce the tax they pay, regardless of whether they replace furnishings in their property, will also be replaced by a new system that only allows them to get tax relief when they replace furnishings.

Jonathan Adams, director of central London estate agency Napier Watt, warned the moves could mean that "f ewer landlords will come into the market, there will be a lack of supply and rents will rise.

"The other issue is that because the stamp duty hike won't come in until April, we could see a rush of landlords buying before then, further pushing up prices in the short term."

Doug Crawford, CEO of My Home Move, said: "The stamp duty changes will turbo-charge the housing market over the next four months as buy-to-let landlords and holiday home buyers race to beat the deadline before the changes bite in April.

"This will inevitably push up property prices in the short term, especially in locations popular with buy-to-let investors, such as London."

Peter Rollings, CEO of estate agent Marsh and Parsons, said: " This new measure needs to be carefully monitored to ensure it doesn't have the unintended consequence of limiting lettings supply and therefore pushing up rents."

Paul Smee, director general of the Council of Mortgage Lenders (CML), said: "Additional stamp duty on buy-to-let transactions comes hot on the heels of the forthcoming tax changes to landlords already announced.

"Government will need to keep a careful eye on the cumulative effects; with the private rented sector housing around a fifth of the population, we do need to avoid unintended consequences."

Paul Emery, real estate tax partner and head of stamp taxes at PwC, said the recent measures seem to indicate the Chancellor is encouraging a shift away from amateur landlords in the residential rental sector.

He said: "Buy-to-let and second home owners will now need more funds to enter the market as a bigger chunk of their deposit will be spent on stamp duty."

Campbell Robb, Shelter's chief executive, said: "We welcome measures to increase stamp duty for buy-to-let and second homes, and that this money will be spent to build more homes.

"But the Chancellor can't ignore the fact that home ownership schemes like starter homes or shared ownership won't work for many, so building more genuinely affordable homes to rent is still absolutely essential.

"Especially when there are plans to force councils to sell off large swathes of their social homes, and in the wake of worrying new cuts for those needing support with their housing costs, including vulnerable single people."

As part of its new housing package, the Government also unveiled plans to help people buying a home in London.

Under the London Help to Buy equity loan scheme, from 2016 the Government will lend people up to 40% of the price of their home to help them buy a property. Home buyers taking part will need to contribute at least 5% of the property price as a deposit and they will also need a mortgage of up to 55% to cover the remaining cost of the property.

Help to Buy equity loans are already open to both first-time buyers and home movers who want to purchase a new-build home in England. Currently, if buyers are able to pay at least 5% of the value of their home as a deposit, the Government will lend them up to 20% of the rest of the value of the property, alongside a mortgage of up to 75% of the value.

The Government said the higher loan amount it plans to offer in London reflects the property market there.

Richard Donnell, research director at housing market analysts Hometrack, said: "The fundamental problem remains that house prices are being maintained at current unaffordable levels."

He said that "buying our way out of the housing crisis" with subsidies "is not a viable long-term option given the scale and variety of market forces at play across the housing market".