Jenson Button says that McLaren need to keep pushing hard despite another trouble-free day of running for the new MP4-27 in Barcelona.

Button spent his first day on track this week on the third day of running at Catalunya, with the team once again able to complete more than 100 laps over the course of the day.

The 2009 title winner ended the day with the fourth quickest time and he said he was pleased with the continued progress being made - although he warned that the team couldn't afford to relax with a number of rivals also looking strong.

"We've done a lot of reliability work over the past three days - more than 100 laps on each day," he said. "Most of that has been longer runs, getting used to the feeling of the car over a long-run and set-up work for the longer runs.

"We've also been really working hard to understand this year's Pirelli tyres and getting the car to work efficiently around them. That's a key part of the programme this winter.

"There are a lot of cars out there that look competitive: so we'll keep pushing. We should hopefully bring our upgrade package to the next test and that will see us through to the first race in Melbourne."