April 30 (Reuters) - Elevator and escalator maker Schindler cautioned that its positive first-quarter results were flattered by comparison with a year ago when China was in lockdown, pushing down its shares even as it raised its 2021 sales guidance.

The Swiss company's order intake rose versus the same period a year ago, beating market expectations, but was still below the level seen in the first quarter of 2019.

Last year, Schindler's results were hit by the lockdown in China, which accounts for 14% of the group's sales, and supply disruptions that drove up the prices of raw materials.

"Let's not be over-enthusiastic about the first quarter, the comparison to the first quarter of 2020 makes no sense at all," CEO Thomas Oetterli told a conference call.

Investors appeared to take heed, and the company's shares were down 4% at 1200 GMT.

Oetterli said that in the first quarter, Schindler had not yet seen the full impact of the commodity price increases, which he said amounted to 80-90 million Swiss francs ($88-99 million) so far, up from the 50 million francs disclosed in February.

Nonetheless, the company now sees its 2021 revenue growing 4% to 7%, compared with its previous outlook of flat to 5%.

Credit Suisse pointed to the same issue as Oetterli.

"We continue to flag that the first-quarter growth rates are substantially affected by the base effect in China," it said in a note.

Finnish rival Kone reported a decline in order intake on Wednesday and said cost inflation would erode its margins even as first-quarter sales and profit beat expectations.

Schindler's order intake in the January-March period rose 8% year-on-year to 2.94 billion Swiss francs, above analyst expectations of 2.78 billion francs in a company-provided poll, but below the 2.97 billion francs reported in the first-quarter of 2019.

Net profit grew 70% to 213 million francs, above the 173 million francs estimated in the poll.

Schindler also said it would launch a programme to speed up digitisation and address issues such as commodity price inflation. The programme would lead to an incremental cost of up to 270 million francs, it added.

($1 = 0.9083 Swiss francs) (Reporting by Bartosz Dabrowski in Gdansk; Editing by Shounak Dasgupta and Pravin Char)