(Reuters) -The Russian central bank said on Monday it had temporarily suspended publishing data on foreign trade on a monthly basis in the first such suspension since 1997.

The central bank was due to release a foreign trade balance for January-February on Monday, as initially planned, according to its data release schedule.

The central bank did not explain its decision to suspend publication of the foreign trade data, monthly figures for which can be tracked back as far as 1997 on the bank’s website.

In January, the latest data available, Russian foreign trade surplus fell to $21.17 billion from $26.72 billion in the previous month.

Russia is under tough Western sanctions as the United States, the European Union and their allies respond to Moscow’s Ukraine invasion launched on Feb. 24, which the Kremlin calls “a special military operation.”

The sanctions have cut Russia off from the global financial system and Western countries are stepping up the pressure by reducing Russian energy imports.

The central bank had earlier suspended weekly publication of its gold and foreign exchange reserves and also stopped disclosing banking sector statistics.

The bank has resumed publication of this weekly data, which showed that Russian gold and forex reserves had fallen to $606.5 billion as of April 1, down from $643.2 billion days before the invasion.

The Russian energy ministry had earlier suspended a monthly release of oil and gas output data citing technical issues.

Russian oil and gas condensate production declined by 4% in early April from March to 10.58 barrels per day (bpd), Interfax newsagency has said, and analysts have warned of a further up to 1.5 mln bpd fall as buyers cancel cargoes.

(Reporting by Reuters; editing by David Evans and Jane Merriman)