It kept rates at record lows, confirmed that monthly bond purchases would continue at 30 billion euros (£26.11 billion) a month until the end of September, and said it stood ready to expand or lengthen its asset-purchase programme if the inflation outlook worsens.

Attention now turns to ECB President Mario Draghi's 1330 GMT news conference, where he will face questions about the euro's 5.5 percent surge against the dollar since December's rate-setting meeting and may hint at the bank's next policy move.

He could also signal that work has begun on revising the ECB's policy guidance, which would cut a singular focus on asset buys and instead focus its efforts more broadly to include all policy instruments, particularly interest rates.

While a decision to keep policy on hold was in line with consensus expectations, some had envisaged a tweak in the ECB's language after policymakers signalled in minutes of the December meeting that a revision to guidance could be needed in "early" 2018.

"If the outlook becomes less favourable, or if financial conditions become inconsistent with further progress towards a sustained adjustment in the path of inflation, the Governing Council stands ready to increase the asset purchase programme (APP) in terms of size and/or duration," it said in a statement.

With Thursday's decision, the ECB's rate on bank overnight deposits, which is currently its primary interest rate tool, remains at -0.40 percent.

The main refinancing rate, which determines the cost of credit in the economy, is unchanged at 0.00 percent while the rate on the marginal lending facility -- the emergency overnight borrowing rate for banks -- remains at 0.25 percent.

"The Governing Council expects the key ECB interest rates to remain at their present levels for an extended period of time, and well past the horizon of the net asset purchases," the ECB added, repeating its long-standing guidance on rates.

(Reporting by Balazs Koranyi; Editing by Catherine Evans)