BERLIN—The German government is working to curb the influx of migrants into the country despite its welcoming discourse on refugees, statistics released on Tuesday suggest.

Authorities here turned back more undocumented migrants at German borders during the first half of this year and deported more foreigners without residency permits than during all of 2015, according to the latest government figures.

Germany denied 13,324 migrants entry at its borders in the period from January to June—nearly 50% more than the 8,913 people it rejected in 2015, the interior ministry said in a response to a parliamentary inquiry from the opposition Left party published Tuesday. In July, 16,160 entered Germany, bringing the total number of migrants pursuing asylum to 238,424 during the January-July period, according to the latest interior ministry figures published on Monday.

Most of the people who were turned back were denied entry at Germany’s border with Austria. These people failed to provide valid visas or residency permits. The interior ministry said the largest group came from Afghanistan, followed by Syria, Iraq, Iran and Morocco.

The flow of asylum seekers into Germany has slowed this year but remains above the rate of a few years ago.

German authorities deported 13,743 people during the first six months of the year, with most of them being sent back to Albania, Kosovo and Serbia, according to the interior ministry. This compares with 20,888 people who were deported in all of 2015.

But the higher number of deportations contrasts with more than 220,000 foreigners who were technically under orders to leave Germany as of the end of May. Some of them have been granted a temporary reprieve.

German efforts to turn or send back more people come after more than 1 million migrants entered Germany alone in 2015, an inflow German officials say can’t be accommodated again this year.

Following Islamist attacks by refugees in southern Germany last month, German Chancellor Angela Merkel said the violence wouldn’t affect the government’s generous refugee policy.

A poll conducted by Infratest Dimap just after the attacks showed Ms. Merkel’s approval rating plummeting 12 points in a month. The same poll showed widespread dissatisfaction with the government’s refugee policy and rising fears of terrorist attacks.

Berlin reintroduced border controls last September to register new arrivals in Germany, increased pressure on migrations to integrate in society and made it easier to expedite the departure of thousands of people whose asylum requests are denied.

The government’s official figures might overstate the actual number of people who intend to stay in Germany to file asylum claims because Germany’s main digital tallying system doesn’t account for possible multiple registrations in different German states under different identities.

Germany’s federal police, which registers many but not all migrants who enter the country, said 122,593 persons who intended to seek asylum arrived during the first half of this year.