Its European prices are moving upwards for the fourth day natural gas due to continued supply concerns, with just over a week left until the transit agreement between of Russia and her Ukrainian according to the Bloomberg agency.

In particular, natural gas rose as much as 2.4% on Tuesday above 45 euros per megawatt hour, the highest level since early December. Prices have risen more than 10% in four straight sessions, highlighting nervousness in the market as the end of the year approaches.

The looming end of the transit deal coincides with forecasts of colder weather across much of Europe, which may increase demand for natural gas as supplies run down faster than normal. The tight market makes it difficult for traders to secure enough gas for next year as they compete with Asia for supplies.

“Current prices already reflect the end of the transit (between Russia and Ukraine) and the market will definitely see a brief uptick once January comes and the transit really stops,” said Florence Schmit, European energy strategist at Rabobank.

Ukrainian President Volodymyr Zelensky last week said his country would not sell Russian gas unless it had assurances that the Kremlin would not benefit financially while the war continued. A disruption in flows would particularly hit countries such as Slovakia, which has been pushing for an alternative arrangement and warned of potential economic damage if supplies were cut.

Europe as a whole has made efforts to wean itself off Russian gas since the invasion, but some countries still rely on supplies from Moscow. An outage could increase demand for liquefied natural gas (LNG), intensifying competition with Asia, just as some LNG projects face delays.