By Tina Bellon
BERLIN (Reuters) - Voter support rose for German Chancellor Angela Merkel's conservative bloc and fell for the anti-immigrant Alternative for Germany (AfD) party, a poll showed on Friday.
The "Deutschlandtrend" survey for national broadcaster ARD, widely regarded as Germany's most authoritative poll and conducted as three states prepare for elections, showed Merkel's CDU/CSU bloc had gained two percentage points to 37 percent.
The party has been losing ground in recent months as many voters have turned against the chancellor's decision to open Germany's borders to refugees fleeing wars in the Middle East, which resulted in the arrival of 1.1 million migrants last year.
In an effort to reduce the flow, lawmakers on Thursday agreed tougher rules for asylum seekers, including making it easier to deport foreign nationals who commit crimes. It was the second package of measures to toughen immigration rules since October.
Migrant arrivals into Germany have also fallen sharply in recent days, due mainly to bad weather and a bottleneck as border restrictions by countries further south along the migrant route kick in, German federal police said.
On Wednesday, just 140 migrants reached Germany, compared with daily peaks of up to 10,000 last year.
The government has acknowledged that the influx is chaotic and that it cannot keep track of all migrants as many register in Germany and then leave the country without de-registering.
In a response to an inquiry by the hard-left Linke party, the government said the whereabouts of 13 percent of all migrants - more than 140,000 people - registered last year were unknown.
The compilers of Friday's opinion poll made no direct link between refugee numbers and the level of support for Merkel, but previous polls showing the one rising while the other falls suggest a correlation.
Deutschlandtrend, which questioned 1,028 voters on Tuesday and Wednesday, also showed support falling for the AfD, a relatively new party pushing an anti-immigrant agenda and which dropped by two points to 10 percent, making it the fourth strongest nationwide.
The first gauge of the German public's stance on the migrant crisis takes place on March 13, when voters in wealthy south-western Baden-Wuerttemberg, in neighboring Rhineland-Palatinate and in Saxony-Anhalt in the east will cast state-level ballots.
They will be Germany's first regional elections since last autumn.
(Additional reporting by Thorsten Severin; Editing by Joseph Nasr and Gareth Jones)