LONDON – European stock indexes opened lower and the euro dropped below 99 cents for the first time in twenty years after Russia said gas supply down its main pipeline to Europe would stay shut.

European gas prices jumped as much as 30 percent on Monday.

Germany announced on Sunday around $65 billion of support to help protect Germans from soaring inflation.

Finland and Sweden announced plans to offer liquidity guarantees to power companies in their countries.

At 0743 GMT, the MSCI world equity index, which tracks shares in 47 countries, was down 0.5 percent on the day. Europe's STOXX 600 was down 1.5 percent, not far from a seven-week low .

London's FTSE 100 was 0.8 percent lower and Germany's DAX was down 2.9 percent.

A public holiday in US markets means lower liquidity, which could lead to outsized market moves.

The euro was trading around $0.99185, down 0.4 percent on the day. It slid during Asian trading hours and hit $0.9876 in early European hours, its lowest since 2002.

Euro zone government bond yields rose, with Italian yields heading towards 4 percent.

The European Central Bank (ECB) meets later this week and is expected to deliver its second big rate hike in an attempt to combat inflation.

"Sky-high energy prices, the risk of gas shortages and the fiscal and regulatory response will shape the outlook for Eurozone GDP and inflation much more than anything the ECB may do with rates," said Berenberg chief economist Holger Schmieding in a client note.

Meanwhile in the UK, Liz Truss is expected to be named as Britain’s next prime minister later on Monday. She is poised to take power at a time when the country faces a cost of living crisis, industrial unrest and a recession.

The British pound was down around 0.4 percent at $1.1476, but flat against the euro at 86.405 pence.

The US dollar index was steady and the risk-sensitive Australian dollar was near a seven-week low.

Oil prices rose more than $2 a barrel as investors waited for an OPEC+ meeting later in the day. Since March's multi-year highs, oil prices have fallen due to concerns that interest rate rises may slow global economic growth.

Other PMI survey data on Monday showed that Germany's services sector contracted for a second month running in August, while Spain's services sector expanded at its slowest rate since January