Nikkei climbs, buoyed by construction and drugs

(Updates to midsession)

TOKYO, May 23 (Reuters) - Japan's Nikkei stock average climbed 0.7 percent on Friday, buoyed by construction and pharmaceutical firms after news that Roche Holding AG (ROG.VX) will increase its stake in partner Chugai Pharmaceutical Co Ltd (4519.T), though gains were stemmed by trading firms hit by lower oil prices.

Construction firm Chiyoda Corp (6366.T) extended gains made after a brokerage upgrade, surging 10.4 percent.

The Nikkei .N225 gained 102.50 points to 14,080.96 after an early foray into negative territory. The broader Topix was up 0.6 percent at 1,387.89. (Reporting by Elaine Lies,)