Dutch riot police have broken up a rally in support of President Recep Tayyip Erdogan hours after a minister was refused entry to the Turkish consulate in Rotterdam.

The Turkish minister was then escorted to the German border and expelled.

Police used water cannons to break up the protesters, who had gathered outside the consulate as the diplomatic row between the two nations escalated.

Protesters were reportedly throwing bottles and mobbing police cars.

Fatma Betul Sayan Kaya, Turkey's minister of family and social policies, had arrived by road on Saturday ahead of a rally planned to help harness the votes of Turks living in the Netherlands.

They will be voting in a referendum next month on whether to expand Mr Erdogan's powers.

But when she arrived, Dutch authorities refused to allow her entry to the consulate, sparking a stream of angry tweets.

Ms Kaya was then escorted by police to the German border, Dutch Prime Minister Mark Rutte confirmed early on Sunday morning.

In a Facebook post, Mr Rutte said attempts to find a "reasonable solution" to the countries' differences had proved "impossible", while dismissing Ms Kaya's arrival in Rotterdam as "irresponsible".

What is the row about?

Turkey is holding a referendum on 16 April on whether to turn from a parliamentary to a presidential republic, more akin to the United States.

If successful, it would give sweeping new powers to the president, allowing them to appoint ministers, prepare the budget, choose the majority of senior judges and enact certain laws by decree.

What's more, the president alone would be able to announce a state of emergency and dismiss parliament.

In order to get it passed, Mr Erdogan needs to get the votes of both those citizens living in, and out, of Turkey.

There are 5.5 million Turks living outside the country, with 1.4 million eligible voters in Germany alone - and the Yes campaign are keen to get them on side.

So a number of rallies have been planned for countries where large numbers of voters currently live, including Germany, Austria and the Netherlands.

However, Mr Erdogan's supporters have found themselves blocked from holding these rallies.

Why are countries trying to prevent the rallies?

Many of the countries have cited security concerns as the official reason the rallies have been banned or moved.

Austrian Foreign Minister Sebastian Kurz said Mr Erdogan was not welcome to hold rallies as this could increase friction and hinder integration.

Dutch Prime Minister Mark Rutte said the Netherlands asked Turkey to desist as they feared "compromised public order and security".

However, many European nations have also expressed deep disquiet about Turkey's response to the July coup attempt and the country's perceived slide towards authoritarianism under President Erdogan.

Germany in particular has been critical of the mass arrests and purges that followed - with nearly 100,000 civil servants removed from their posts.

What has Turkey's response been?

Mr Erdogan has lashed out at Germany and the Netherlands, denouncing the Dutch government as "Nazi remnants and fascists", while accusing Germany of "Nazi practices".

German Chancellor Angela Merkel has condemned the Nazi jibe as "unacceptable", while Mr Rutte dismissed it as a "crazy remark".

But Mr Erdogan escalated the rhetoric after the Netherlands banned his foreign minister Mevlut Cavusoglu from entering the country by plane by threatening to block Dutch flights.

He said: "Ban our foreign minister from flying however much you like, but from now on, let's see how your flights will land in Turkey."

Mr Cavusoglu also warned Turkey would impose heavy sanctions if his visit was blocked.

Ms Kaya's arrival, by road, was seen as a further provocation by Turkey on the part of the Dutch - although Mr Rutte says his government remains "in favour" of speaking with Mr Erdogan and his colleagues to find a resolution.