BERLIN (Bloomberg) - German Chancellor Angela Merkel said she planned to serve a full four-year term if re-elected and defended her government against accusations that she's faltered on public infrastructure investment.

"I made clear when I announced my re-election bid that I would run for four years," Dr Merkel said in an interview with ARD television on Sunday (July 16), 10 weeks before the national election. A full fourth term would extend her chancellorship to 16 years through 2021.

The 62-year-old German leader also defended her fiscal policy after Social Democratic challenger Martin Schulz pledged to increase public investment. Dr Merkel said her government has already increased spending "massively" on broadband expansion, roads and pre-schools.

The German government's problem is rather bureaucratic barriers to allocating funds, which require accelerated planning processes, she said.

"At this point we can't spend the money that we have," Dr Merkel said.

Merkel's Christian Democratic-led bloc had 38 per cent support, 13 points ahead of the rival Social Democrats, according to an Emnid poll published in Bild am Sonntag newspaper on Sunday. All other parties had less than 10 per cent.