More than ten million people have now fled their homes in Ukraine because of the Russian invasion, according to the the United Nations High Commissioner for Refugees.

As well as the four million who have left for neighbouring countries, another estimated 6.5 million people are thought to be displaced inside the war-torn country itself.

The UN's figure is based on research carried out by the International Organisation for Migration (IOM) between 9 and 16 March.

Of the 2,000 internally displaced people it surveyed:

The IOM estimates that more than half of the people who are internally displaced are women, and many are deemed particularly vulnerable because they are pregnant, have a disability or are a victim of violence.

The UN, which is working alongside other organisations to provide help to people in Ukraine, says it is offering humanitarian assistance "wherever necessary and possible". This includes:

As well as the 6.5 million people who have left their homes, about 12 million are thought to be stranded or unable to leave areas affected by the fighting.

Refugees are also crossing to neighbouring countries to the west, such as Poland, Romania, Slovakia, Hungary and Moldova.

The UN says that as of 29 March, four million people have left Ukraine:

Some people have travelled from Moldova into Romania and so are included in both countries' totals.

Trains heading towards Ukraine's border have been packed, and there have been long queues of traffic on roads leading out of the country.

Refugees don't need all their official documents, but it is helpful if they can provide provide identification cards or passports, birth certificates of children travelling with them and and medical documentation.

To get refugee status, they need to be Ukrainian citizens or people legally living in Ukraine, such as foreign students.

There have been reports of people from African countries being prevented from leaving Ukraine.

In countries bordering Ukraine, refugees can stay in reception centres if they can't stay with friends or relatives. They are given food and medical care, and information about onward travel.

The EU has granted Ukrainians who flee the war a blanket right to stay and work throughout its 27 member nations for up to three years.

They will also receive social welfare and access to housing, medical treatment and schools.

The government of Poland, which has received the highest number of refugees, has said it will need more money than the EU is currently offering in order to host the number of people arriving there.

Moldova, which has by far the largest concentration of refugees per capita, has also appealed for international help in dealing with the numbers arriving.

The UK launched a family visa scheme for Ukrainians who have an immediate or extended family member in the UK.

As of 29 March, 22,800 Ukraine family visas had been issued, against 31,200 applications received.

After the UK government was criticised for the speed and scale of its response, it also launched the Homes for Ukraine scheme.

Under this scheme, people in the UK can nominate an individual or family to stay with them rent-free for at least six months.

As of 29 March, 2,700 Ukraine sponsorship visas had been issued out of 28,300 applications.

Refugees who come via the scheme will be able to live and work in the UK for up to three years, and access healthcare, welfare and schools.

Applications are made online, and both hosts and refugees will be vetted. Hosts will receive £350 a month and there will be no cap on the numbers able to come to the UK.