The European Union has warned that it expects action from states capable of helping the prosecution of those responsible for shooting down Malaysia Airlines Flight MH17 as Dutch royalty and the victims’ relatives gathered Monday to unveil a monument to the 298 victims.

A tree was also planted for each of the victims amid a field of sunflowers near Amsterdam’s Schiphol Airport and the names of those killed read out to a crowd of more than 2000.

Dutch King Willem-Alexander and Queen Maxima attended the unveiling of the monument on the third anniversary of the atrocity on July 17, 2014.

The Boeing 777 was travelling between Amsterdam and Kuala Lumpur when it was struck by a Russian-made BUK missile.

An investigation by the Dutch Safety Board found the missile was fired from territory held by Russian separatists on July 17, 2014. The attack killed 298 people from 17 countries, including 38 from Australia and 196 from the Netherlands.

The investigation found the missile was taken from Russia to the Rebel-held territory on the morning of July 17 and returned the next day. It narrowed down the launch site to a specific field near the then rebel-held village of Pervomaiskyi. Russia has denied involvement and denounced the conclusions as politically based.

Investigators have identified 100 people they want to interview in connection with the crime but they have not been officially named.

The Netherlands is moving to prosecute the perpetrators with support from other countries such as Britain and Australia. It earlier this month signed a bilateral treaty on international legal cooperation with the Ukrainian government that will allow this to happen.

Australian Foreign Minister Julie Bishop told the ABC Insiders program on Sunday that this may have to be done in absentia.

“There have been reports that some of the witnesses have been detained in Russia. Well, I certainly urge Russia to comply with the Security Council resolution and do all it can to help bring these people to account,” Bishop said.

EU foreign policy chief Federica Mogherini said on Monday the loss of MH17 remained a constant source of sorrow and sadness for the European Union.

Mogherini said the EU and its member states reiterated their full support of the work of the Joint Investigation Team charged with the criminal investigation.

“As the Joint Investigation Team's work as regards individual suspects continues, it is crucial that the investigators can complete their work, independently and thoroughly,’’ he said in a statement.

 “We welcome the steps taken by the countries involved to come to an effective prosecution, as well as their decision to opt for the Dutch national justice system embedded in international cooperation and support as an important step towards bringing those responsible for downing flight MH17 to justice.

“To ensure that those responsible for the downing of MH17 are held accountable and brought to justice, the criminal investigation needs the continuing support of the international community.

“We expect all the States that are in a position to assist the investigation and prosecution of those responsible to do so, as demanded by United Nations Security Council Resolution 2166.”

The United States also joined the call with a State Department official urging other states to “cooperate fully in order to ensure those responsible are brought to justice”.