The shortfall in Britain's trade in goods with the rest of the world widened to a record of nearly £6 billion in November from just over £5 billion in October.
Imports of oil exceeded exports for a fifth month after National Statistics revised a small surplus reported for October into a deficit.
November's surplus from trade in services - including banking, insurance and travel - slipped by £190 million to £1.48 billion.
Overall, imports hit a new seasonally adjusted record, boosted by an inward surge in cars as well as a £289 million jump in imports of so-called erratic items such as aircraft, ships and gemstones.
At the same time, exports suffered their first month-on-month setback since July, dipping by £237 million to £26.82 billion.
Not counting oil and erratics, exports of goods were £165 million down on October at £15.18 billion.
Over the latest three months overall trade shows a slight improvement - entirely because of payments by British insurers in August for claims arising from hurricane Katrina. NS has now revised these upwards to £1.9 billion from a previous estimate of £1.5 billion.
This has the effect of lowering the overall trade gap for the three months to November to £12 billion from £12.8 billion in June/August.
NS estimates that the trend in Britain's trade gap has been "fairly flat" in recent months.
Trade in goods with non-EU countries resulted in a £3.02 billion shortfall in November, up from £2.28 billion in October.
With the EU, though, the deficit from trade in goods widened only by a marginal £76 million to £2.95 billion.
While the headline numbers were worse than most analysts had expected, some saw encouraging signs, including a £131 million rise in exports to EU countries following up a £233 million improvement in October.
"We had a slump in export volumes to non-EU countries, but exports are still above the level of the third quarter," said Geoffrey Dicks, UK economist at RBS Financial Markets.
NS warned that its numbers are still being distorted by the "missing trader inter-community" frauds - mostly VAT swindles in which large quantities of mobile phones are moved in and out of the UK.
Originally this concerned only trade with EU countries, but recently some non-EU countries have become involved.
"However, the import adjustment is applied only to EU imports as the goods return to the UK via the EU - but it is this part of the trading chain that is not recorded," NS explained.
"Fraud, by its very nature, is difficult to measure reliably."