Jan 4 (Reuters) - Alexion Pharmaceuticals Inc on Wednesday filed its delayed third-quarter 2016 financial report with U.S. regulators and said an investigation into allegations regarding sales practices found no need to restate previous financial results.

Shares of Alexion, which rose 3.7 percent to close at $127.11 in regular trading, were up more than 6 percent after hours.

The biotechnology company disclosed in November it was investigating allegations made by a former employee regarding sales practices involving its costly blood disorder drug Soliris.

Alexion said Wednesday its board's audit and finance committee found no instances of improper revenue recognition, but did find a material weakness in internal controls over financial reporting as of December 31, 2015 and subsequent quarters. This was attributed to "senior management not setting an appropriate tone at the top."

Alexion said it would report full-year 2016 results, and its financial outlook, on February 16. The company said it still expected full-year 2016 adjusted earnings per share of $4.50 to $4.65 on revenue of $3.05 billion to $3.10 billion.

Alexion reported third quarter results in October but delayed filing its 10-Q financial report for the period while it carried out the internal investigation.

The company last month announced the resignations of its chief executive officer and chief financial officer.

"We have already initiated remedial actions to maintain a strong internal control environment and are committed to setting a tone at the top that is fully aligned with our ethical standards and values," interim CEO David Brennan said in a statement.

(Reporting by Deena Beasley; Editing by Andrew Hay)