Poland's ambassador to Israel was spat at while sitting in his car in Tel Aviv, Israeli police said, and the Polish government condemned the incident, which coincided with rising tensions between the two countries.
"I am very worried to hear of a racist attack on @PLinIsrael ambassador @mmagierowski. Poland strongly condemns this xenophobic act of aggression. Violence against diplomats or any other citizens should never be tolerated," Polish Prime Minister Mateusz Morawiecki wrote in a tweet on Wednesday.
An Israeli police spokesman said on Wednesday a 65-year-old Israeli man was arrested over Tuesday's spitting incident. Israel's Walla News site said the suspect was brought to court on Wednesday and released on bail. It quoted the judge as saying the alleged attack against a foreign diplomat was shameful.
The Polish Foreign Ministry summoned Israel's ambassador to Warsaw, Anna Azari, over the matter, a ministry spokeswoman told the state-run news agency PAP.
"The event is under police investigation. We express our fullest sympathy to the ambassador and our shock at the attack," Israeli Foreign Ministry spokesman Emmanuel Nahshon said.
Polish-Israeli relations have deteriorated in recent months over accusations that Warsaw's nationalist PiS government has tolerated a revival of anti-Semitic behaviour, a charge it denies.
Hundreds of far-right supporters marched in Warsaw on Saturday in protest against a U.S. law on the restitution of Jewish property seized during or after World War Two, an increasingly prominent issue in Polish election campaigns.
A lawyer for the man suspected of spitting at the ambassador was quoted by Walla News as saying he had been turned away from the Polish Embassy on Tuesday after trying to inquire about restitution.
The PiS government has said that Poland - which had one of the world's biggest Jewish communities before it was almost entirely wiped out by Nazi occupiers - was a victim of World War Two and so should not be saddled with any financial obligations.
In response to the ultra-nationalist march, the World Jewish Congress urged Polish religious and political leaders on Wednesday to unequivocally condemn anti-Semitism.
On Monday the Polish government cancelled a visit by an Israeli delegation as it learned that the Israelis intended to bring up the restitution issue, the Foreign Ministry said.