FRANKFURT—The European Central Bank on Wednesday maintained its limits on emergency loans to Greek commercial banks, an ECB spokesman said, a decision that likely will keep capital controls in place at least through Sunday’s referendum on the country’s willingness to meet creditor demands.

The ECB also made no changes to the amount of collateral banks must post to obtain the liquidity although the topic was discussed, according to a person familiar with the matter, a day after Greece defaulted on €1.55 billion ($1.72 billion) it owed the International Monetary Fund and the country’s bailout program expired, leaving Athens with no outside support.

On Sunday, the ECB froze emergency liquidity assistance, or ELA, at around €89 billion after letting it climb steadily in recent months after Greek government debt was in February shut out as collateral for standard ECB lending facilities that carry a lower interest rate than ELA.

The decision at a meeting Wednesday of the ECB’s governing council largely keeps Greek banks in limbo: They can’t borrow additional central bank money to finance deposit outflows; but they won’t have to repay the existing stock of loans either. Greek banks have been closed since Monday, and ATM withdrawals are limited to €60 a day.

It also underscores how loathe ECB officials are to making any decisions that would upend the political process as it reaches its decisive phase. Greek voters are due to vote July 5 on whether to accept a recent proposal by the institutions overseeing the country’s now-expired bailout—the ECB, IMF and European Commission—or reject it as the left-wing government has urged.