In a letter sent to the chief of staff, 37 pilots threatened to not attend a training day due on Wednesday.

"We will continue to serve the Jewish and democratic State of Israel at all times and across borders... (but) we have decided to take a one day break to talk about the disturbing processes the country is going through," explained one of the pilots, speaking anonymously as his identity cannot be published.

The pilots' statement was printed in Israeli media on Sunday.

Judicial reform is a cornerstone of Prime Minister Benjamin Netanyahu's administration, an alliance with ultra-Orthodox and extreme-right parties which took office in late December.

Netanyahu presents the overhaul as key to restoring balance between the branches of government in a system he believes gives judges too much power over elected officials.

Thousands of Israelis have taken part in mass rallies since January to protest legal reforms, which if passed in parliament, would deny the Supreme Court the right to strike down any amendments to so-called Basic Laws, Israel's quasi-constitution.

Military service is compulsory in Israel, and reservists are often called up each year for limited periods.

However, in recent weeks, calls by reservists to refuse to serve have grown.

Former defence minister Benny Gantz has called on all reservists "to continue to fulfil their duties" and to defend Israel's "existence by serving in the military".

While the names of the airforce pilots are barred from publication by the military censor, petitions signed by reservists from other branches of the military have been published in recent weeks.

Opposition leader Yair Lapid said Sunday that he was "opposed to any form of refusal to serve", following the statement by his former spokesman Roi Konkol who had earlier claimed "not to want to serve the army under Netanyahu's regime".