London was the only region of Britain to register an increase in the supply of fresh homes coming to market in the first two weeks of 2021, according to analysis.
Across Britain generally, the supply of new properties dipped by 12% compared with early 2020, but in the capital there was a 12% increase, Zoopla said.
The new stock in London is mainly made up of flats, the research suggests.
This is partly due to home-owners looking to trade up to houses, and investors looking to sell homes as rents fall, Zoopla said.
At the other end of the spectrum, Scotland recorded the sharpest fall in new homes coming to the market in early 2021 compared with a year earlier, with a 19% decrease, followed by the North East (down 14% fall), the South West (also a 14% decline) and the South East (a 13% drop), the report said.
The current stamp duty holiday is due to end on March 31 2021, which has boosted activity among home-buyers as they rush to beat the deadline.
Zoopla said around 55% of sales agreed in January would normally complete by the end of the first quarter, but the proportion this year is likely to be lower.
It estimates there is a risk that up to 70,000 sales agreed in 2020 may miss the deadline.
The report also highlighted the case of Lauren Joselyn, 34, a PR consultant from Clapham in south London, who is expecting her first baby soon and wants to buy a family home in East or West Sussex.
She said: “So far, we haven’t had any luck in finding our first family home. There is fierce competition for family-sized homes in our search area. We made an offer on a doer-upper in the autumn, but were outbid.
“The closer we got to Christmas, the less there seemed to be on the market, and the supply of new properties doesn’t seem to have increased, even though we’re now well into the new year. It feels like a lack of properties is a characteristic of the Covid market.”
She added that in current pandemic conditions: “I don’t think sellers want prospective buyers in their homes.”
Current Government housing market guidance in England states that initial viewings should be done virtually wherever possible.
People viewing properties generally need to wear a suitable face covering and viewings should be arranged by appointment. Sellers are recommended to vacate their property during viewings.
Everyone involved in the moving process must follow social distancing to minimise the spread of coronavirus.
Richard Donnell, research and insight director, Zoopla, said potential sellers appear to be waiting for coronavirus case numbers to fall much further before listing their home.
He added: “The rush to beat the stamp duty deadline continues and sellers who agreed to buy a home in 2020 would reasonably expect to make the stamp duty saving.
“Delays mean we expect up to 70,000 sales agreed in 2020 to miss the deadline.”