Net migration is calculated as the difference between the total number of people entering the country and leaving it.
"Net long-term migration to the UK was estimated to be 298,000 in the year ending September 2014, a statistically significant increase from 210,000 in the previous 12 months", the Migration Statistics Quarterly Report said, adding that this figure is only 22,000 migrants short of the peak numbers of 2005.
According to the document, a total of 624,000 persons immigrated to Britain in the observed period, compared to 530,000 in the previous year.
"There were statistically significant increases for immigration of non-EU citizens (up 49,000 to 292,000) and EU (non-British) citizens (up 43,000 to 251,000)," the report said.
Some 271,000 people came to the United Kingdom for work, 175,000 – for study, 90,000 immigrated accompanying or joining family and 24,914 sought asylum, according to the study.
The migration level revealed by the current report, which is the last set of quarterly figures the ONS is set to publish before the UK general elections in May, is well above the figures for 2010 when the current Prime Minister David Cameron came to power.
At the time of the 2010 elections, net long-term migration to the United Kingdom stood at 252,000 people.
In 2011, Cameron pledged to reduce the migration to "tens of thousands."
